Semiconductor device and manufacturing method thereof

ABSTRACT

The semiconductor device includes a thin film transistor; a first interlayer insulating film over the thin film transistor; a first electrode electrically connected to one of a source region and a drain region, over the first interlayer insulating film; a second electrode electrically connected to the other of the source region and the drain region; a second interlayer insulating film formed over the first interlayer insulating film, the first electrode, and the second electrode; a first wiring electrically connected to one of the first electrode and the second electrode, on the second interlayer insulating film; and a second wiring not electrically connected to the other of the first electrode and the second electrode, on the second interlayer insulating film; in which the second wiring is not electrically connected to the other of the first electrode and the second electrode by a separation region formed in the second interlayer insulating film.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to semiconductor devices capable ofcommunication with the use of contactless means such as wirelesscommunication, and a manufacturing method thereof. In particular, thepresent invention relates to a semiconductor device that is formed overan insulating substrate of glass, plastic, or the like and amanufacturing method thereof.

2. Description of the Related Art

With development of computer technologies and improvement of imagerecognition technologies, data identification methods utilizing a mediumsuch as bar codes have spread widely and have been used foridentification of product data and the like. It is expected that theamount of data to be identified will further increase in the future. Onthe other hand, data identification utilizing bar codes isdisadvantageous in that a bar code reader is required to be in contactwith the bar codes, and that the amount of data capable of being storedin the bar codes is small. Therefore, contactless data identificationand increase in the storage capacity of a medium are required.

In view of the foregoing requirements, a semiconductor device capable ofwireless communication that uses an IC (also referred to as an ID chip,an IC chip, an IC tag, an ID tag, a wireless chip, or an RFID) has beendeveloped recently. The data is stored in a memory circuit in the IC inthe semiconductor device and is read by contactless means, generallywireless means. Practical application of such a semiconductor devicewill allow commercial distribution and the like to be simplified andmade cheaper while ensuring high security.

An overview of an individual recognition system using theabove-described semiconductor device capable of wireless communicationthat uses an IC is described with reference to FIG. 2, FIG. 3, and FIGS.4A and 4B. FIG. 2 illustrates an overview of an individual recognitionsystem for recognizing individual data on a bag without contact.

A semiconductor device 221 storing particular individual data isattached to or embedded in a bag 224. A signal is transmitted to thesemiconductor device 221 from an antenna unit 222 which is electricallyconnected to an interrogator (also referred to as a reader/writer) 223.When receiving the signal, the semiconductor device 221 sends back theindividual data that the semiconductor device holds to the antenna unit222. The antenna unit 222 sends the individual data to the interrogator223, and the interrogator 223 identifies the individual data. In thismanner, the interrogator 223 can obtain the individual data on the bag224. Furthermore, this system enables physical distribution management,counting, exclusion of a counterfeit, and the like.

For example, such a semiconductor device has a structure shown in FIG.3. A semiconductor device 200 includes an antenna circuit 201, arectifier circuit 202, a stabilizing power supply circuit 203, anamplifier 208, a demodulation circuit 213, a logic circuit 209, a memorycontrol circuit 212, a memory circuit 211, a logic circuit 207, anamplifier 206, and a modulation circuit 205.

For example, the antenna circuit 201 includes an antenna coil 241 and acapacitor 242 (FIG. 4A). For example, the rectifier circuit 202 includesdiodes 243 and 244 and a capacitor 245 (FIG. 4B).

An operation of such a semiconductor device capable of wirelesscommunication that uses an IC is described below. A wireless signalreceived by the antenna circuit 201 is half-wave rectified by the diodes243 and 244 and then smoothed by the capacitor 245. The smoothed voltagecontaining a plurality of ripples is stabilized by the stabilizing powersupply circuit 203, and the stabilized voltage is supplied to thedemodulation circuit 213, the modulation circuit 205, the amplifier 206,the logic circuit 207, the amplifier 208, the logic circuit 209, thememory circuit 211, and the memory control circuit 212.

Moreover, a signal received by the antenna circuit 201 is input to thelogic circuit 209 as a clock signal through the amplifier 208. Further,a signal input from the antenna coil 241 is demodulated by thedemodulation circuit 213 and input as data to the logic circuit 209.

In the logic circuit 209, the input data is decoded. Since theinterrogator 223 sends data after having encoded it, the logic circuit209 decodes the data. The decoded data is sent to the memory controlcircuit 212, and then data stored in the memory circuit 211 is read out.

It is necessary that the memory circuit 211 be a nonvolatile memorycircuit which is capable of storing data even when the power is OFF, anda ROM (Read Only Memory), or the like is employed (Japanese Patent No.3578057).

As a transmitted/received signal, 125 kHz, 13.56 MHz, 915 MHz, 2.45 GHz,or the like may be employed, to each of which the ISO standard or thelike is applied. In addition, a standard is also set for a modulationand demodulation system in transmission/reception.

SUMMARY OF THE INVENTION

In order to manufacture the above-described semiconductor device capableof wireless communication that uses an IC, a nonvolatile memory circuit,for example, a mask ROM has been necessarily formed as described above.

However, the mask ROM (hereinafter simply referred to as a ROM) can onlywrite data at the time of manufacturing. Therefore, data is written atthe same time as the manufacture of the mask ROM in manufacturing thesemiconductor device.

Individual data of an individual semiconductor device such as an IDnumber is stored in a ROM. The individual data such as the ID numbervaries between individual semiconductor devices. However, since the ROMis generally manufactured by photolithography, in order to vary theindividual data such as the ID number between the individualsemiconductor devices, a photomask has to be formed for everysemiconductor device. Thus, when the individual data such as the IDnumbers are formed to be all different, a heavy burden is imposed onmanufacturing cost and the manufacturing process.

The ID number is a number for identifying each semiconductor device, andeach semiconductor device has a different ID number.

In consideration of such a situation, the present invention providessemiconductor devices capable of wireless communication each using an ICprovided with a ROM having individual data such as an ID number that isdifferent from those of other semiconductor device, and a manufacturingmethod of the semiconductor devices.

In order to solve the above-described problems, in semiconductor devicescapable of communication via wireless communication according to thepresent invention, one feature is that a wiring is soaked in anelectrolyte and applied with a voltage, thereby dissolving a wiringmaterial. Thus, a wiring whose electric connection is blocked and awiring whose electric connection is maintained are formed, and differentdata is written to each of the semiconductor devices. More specifically,among electrodes or wirings which are electrically connected to activelayers of TFTs for forming a memory cell array of a memory circuit in asemiconductor device, an electrode or wiring whose electric connectionis desired to be blocked is soaked in an electrolyte and applied with avoltage, thereby dissolving the electrode or wiring. In this manner, anelectrode or wiring whose electric connection is blocked and anelectrode or wiring whose electric connection is maintained can beseparately formed.

In the present invention, the above-described different data to eachsemiconductor device means individual data such as an ID numbercorresponding to an individual semiconductor device.

In the semiconductor device (also referred to as an ID chip, an IC chip,an IC tag, an ID tag, a wireless chip, or an RFID) capable ofcommunication via wireless communication of the present invention, a ROMand a logic circuit are formed. Each of the ROM and the logic circuitincludes a thin film transistor (TFT).

The present invention relates to a semiconductor device including a thinfilm transistor over a substrate which includes an island-shapedsemiconductor film including a channel forming region, a source regionand a drain region, a gate insulating film, and a gate electrode; afirst interlayer insulating film over the thin film transistor; a firstelectrode which is formed over the first interlayer insulating film andelectrically connected to one of the source region and the drain region;a second electrode which is formed over the first interlayer insulatingfilm and electrically connected to the other of the source region andthe drain region; a second interlayer insulating film formed over thefirst interlayer insulating film, the first electrode, and the secondelectrode; a first wiring which is formed on the second interlayerinsulating film and electrically connected to one of the first electrodeand the second electrode; and a second wiring which is formed on thesecond interlayer insulating film and not electrically connected to theother of the first electrode and the second electrode. The second wiringis not electrically connected to the other of the first electrode andthe second electrode by a separation region which is formed in thesecond interlayer insulating film.

The present invention relates to a manufacturing method of asemiconductor device, including the steps of forming over a substrate anisland-shaped semiconductor film, a gate insulating film, and a gateelectrode; adding an impurity imparting one conductivity type into theisland-shaped semiconductor film so as to form a channel forming region,a source region, and a drain region in the island-shaped semiconductorfilm; forming a first interlayer insulating film so as to cover theisland-shaped semiconductor film, the gate insulating film, and the gateelectrode; forming a first electrode which is electrically connected toone of the source region and the drain region, over the first interlayerinsulating film; forming a second electrode which is electricallyconnected to the other of the source region and the drain region, overthe first interlayer insulating film; forming a second interlayerinsulating film so as to cover the first interlayer insulating film, thefirst electrode, and the second electrode; forming a first contact holereaching the first electrode, in the second interlayer insulating film;forming a second contact hole reaching the second electrode, in thesecond interlayer insulating film; soaking the first electrode and thesecond electrode in an electrolyte and applying voltage to one of thefirst electrode and the second electrode so as to dissolve the one ofthe first electrode and the second electrode and to form a separationregion; forming a first wiring which is not electrically connected tothe one of the first electrode and the second electrode, in one of thefirst contact hole and the second contact hole and on the secondinterlayer insulating film; and forming a second wiring which iselectrically connected to the other of the first electrode and thesecond electrode through the other of the first contact hole and thesecond contact hole, on the second interlayer insulating film.

In the present invention, the thin film transistor is used in anonvolatile memory circuit.

The present invention relates to a semiconductor device including afirst thin film transistor over a substrate which includes a firstisland-shaped semiconductor film including a first channel formingregion, a first source region and a first drain region, a gateinsulating film, and a first gate electrode; a second thin filmtransistor which includes a second island-shaped semiconductor filmincluding a second channel forming region, a second source region and asecond drain region, the gate insulating film, and a second gateelectrode; a first interlayer insulating film over the first thin filmtransistor and the second thin film transistor; a first electrode whichis formed over the first interlayer insulating film and electricallyconnected to one of the first source region and the first drain region;a second electrode which is formed over the first interlayer insulatingfilm and electrically connected to the other of the first source regionand the first drain region; a third electrode which is formed over thefirst interlayer insulating film and electrically connected to one ofthe second source region and the second drain region; a fourth electrodewhich is formed over the first interlayer insulating film andelectrically connected to the other of the second source region and thesecond drain region; a second interlayer insulating film formed over thefirst interlayer insulating film and the first to fourth electrodes; afirst wiring which is formed on the second interlayer insulating filmand electrically connected to the first electrode; a second wiring whichis formed on the second interlayer insulating film and electricallyconnected to the second electrode; a third wiring which is formed on thesecond interlayer insulating film and not electrically connected to thethird electrode; and a fourth wiring which is formed on the secondinterlayer insulating film and electrically connected to the fourthelectrode. The third wiring is not electrically connected to the thirdelectrode by a separation region which is formed in the secondinterlayer insulating film.

The present invention relates to a manufacturing method of asemiconductor device, including the steps of forming over a substrate afirst island-shaped semiconductor film, a second island-shapedsemiconductor film, a gate insulating film, a first gate electrode, anda second gate electrode; adding an impurity imparting one conductivitytype into the first island-shaped semiconductor film and the secondisland-shaped semiconductor film so as to form a first channel formingregion, a first source region, and a first drain region in the firstisland-shaped semiconductor film and so as to form a second channelforming region, a second source region, and a second drain region in thesecond island-shaped semiconductor film; forming a first interlayerinsulating film so as to cover the first island-shaped semiconductorfilm, the second island-shaped semiconductor film, the gate insulatingfilm, the first electrode, and the second electrode; forming a firstelectrode which is electrically connected to one of the first sourceregion and the first drain region, over the first interlayer insulatingfilm; forming a second electrode which is electrically connected to theother of the first source region and the first drain region, over thefirst interlayer insulating film; forming a third electrode which iselectrically connected to one of the second source region and the seconddrain region, over the first interlayer insulating film; forming afourth electrode which is electrically connected to the other of thesecond source region and the second drain region, over the firstinterlayer insulating film; forming a second interlayer insulating filmso as to cover the first interlayer insulating film and the first tofourth electrodes; forming a first contact hole reaching the firstelectrode, in the second interlayer insulating film; forming a secondcontact hole reaching the second electrode, in the second interlayerinsulating film; forming a third contact hole reaching the thirdelectrode, in the second interlayer insulating film; forming a fourthcontact hole reaching the fourth electrode, in the second interlayerinsulating film; soaking the first to fourth electrodes in anelectrolyte and applying voltage to the third electrode so as todissolve the third electrode and form a separation region; forming afirst wiring which is electrically connected to the first electrodethrough the first contact hole, on the second interlayer insulatingfilm; forming a second wiring which is electrically connected to thesecond electrode through the second contact hole, on the secondinterlayer insulating film; forming a third wiring which is notelectrically connected to the third electrode, in the third contact holeand on the second interlayer insulating film; and forming a fourthwiring which is electrically connected to the fourth electrode throughthe fourth contact hole, on the second interlayer insulating film.

In the present invention, the first thin film transistor and the secondthin film transistor are used in a nonvolatile memory circuit.

Note that in this specification, a semiconductor device refers to alltypes of devices which can function by using semiconductorcharacteristics. An electro-optical device, a semiconductor circuit, andan electronic device are all included in the category of thesemiconductor device.

By the present invention, different individual data such as ID numberscan be easily given to individual semiconductor devices capable ofwireless communication that use ICs.

In this way, reduction of manufacturing time and manufacturing cost of asemiconductor device capable of wireless communication that uses an ICcan be realized.

BRIEF DESCRIPTION OF DRAWINGS

In the accompanying drawings:

FIG. 1 is a cross sectional view of a semiconductor device according tothe present invention;

FIG. 2 is a schematic view of an individual recognition system;

FIG. 3 is a block diagram showing a structure of a conventionalsemiconductor device;

FIGS. 4A and 4B are block diagrams showing structures of a conventionalsemiconductor device;

FIGS. 5A to 5C are cross sectional views of a manufacturing process of asemiconductor device according to the present invention;

FIGS. 6A to 6C are cross sectional views of a manufacturing process of asemiconductor device of the present invention;

FIGS. 7A to 7C are cross sectional views of a manufacturing process of asemiconductor device of the present invention;

FIGS. 8A and 8B are cross sectional views of a manufacturing process ofa semiconductor device of the present invention;

FIGS. 9A and 9B are cross sectional views of a manufacturing process ofa semiconductor device of the present invention;

FIG. 10 is a circuit diagram of a semiconductor device according to thepresent invention;

FIG. 11 is a cross sectional view of a semiconductor device according tothe present invention;

FIG. 12 is a circuit diagram of a semiconductor device according to thepresent invention;

FIG. 13 is a block diagram showing a structure of a semiconductor deviceaccording to the present invention;

FIG. 14 is a block diagram showing a structure of a semiconductor deviceaccording to the present invention;

FIG. 15 is a block diagram showing a manufacturing process of asemiconductor device according to the present invention;

FIGS. 16A to 16D are cross sectional views of a manufacturing process ofa semiconductor device according to the present invention;

FIGS. 17A to 17C are cross sectional views of a manufacturing process ofa semiconductor device according to the present invention;

FIGS. 18A to 18C are cross sectional views of a manufacturing process ofa semiconductor device according to the present invention;

FIGS. 19A and 19B are cross sectional views of a manufacturing processof a semiconductor device according to the present invention;

FIGS. 20A and 20B are cross sectional views of a manufacturing processof a semiconductor device according to the present invention;

FIGS. 21A and 21B are cross sectional views of a manufacturing processof a semiconductor device according to the present invention;

FIGS. 22A and 22B are cross sectional views of a manufacturing processof a semiconductor device according to the present invention;

FIG. 23 is a cross sectional view of a manufacturing process of asemiconductor device according to the present invention;

FIGS. 24A to 24E are top views of semiconductor devices according to thepresent invention;

FIGS. 25A and 25B are top views of semiconductor devices according tothe present invention; and

FIGS. 26A to 26C are top views of a semiconductor device according tothe present invention.

DETAILED DESCRIPTION OF THE INVENTION Embodiment Mode 1

Embodiment modes and embodiments of the present invention will bedescribed with reference to the drawings. It is easily understood bythose skilled in the art that various changes may be made in forms anddetails without departing from the spirit and the scope of theinvention. Therefore, the present invention should not be limited to thedescriptions of the embodiment modes and embodiments below. In addition,in the following drawings, the same reference numerals are commonlygiven to the same components or components having a similar function,and the repetitive description thereof is omitted.

Embodiment Mode 1 will be described with reference to FIG. 1, FIGS. 5Ato 5C, FIGS. 6A to 6C, FIGS. 7A to 7C, FIGS. 8A and 8B, FIGS. 9A and 9B,FIG. 10, FIG. 11, FIG. 12, FIG. 13, FIG. 14, and FIG. 15.

FIG. 10 is a circuit diagram of a mask ROM and includes a column decoder15, a row decoder 16, a memory cell array 11 including n-channel TFTs118 to 121, bit lines (data lines) 24 and 25, word lines W1 and W2, ahigh voltage power supply (VDD) 22, a low voltage power supply (VSS orGND) 23, column switches SW1 to SW4, address lines S1 and S2 which arecontrolled by the column decoder 15, an output line 14, a control line17, and wirings 27 and 28 which are electrically connected to the highvoltage power supply 22.

FIG. 1 is a cross sectional view of the TFT 118 and the TFT 119 includedin the memory cell array 11 shown in FIG. 10. The storage state of themask ROM shown in FIG. 1 is expressed by whether a wiring iselectrically connected to the other of a source region and a drainregion of a TFT for forming a memory cell which is formed in the maskROM. The TFT 118 is electrically connected to the wiring 27, and the TFT119 is not electrically connected to the wiring 28.

For simplicity, FIG. 10 shows a memory cell array for 4 bits. However, anonvolatile memory circuit of the present invention is not limited to 4bits.

In FIGS. 1 and 10, the TFTs 118 to 121 are n-channel TFTs, and the TFT118 includes an island-shaped semiconductor film 131, which is an activelayer, and a gate electrode 103 including a lower-layer gate electrode103 a and an upper-layer gate electrode 103 b as shown in FIG. 1. TheTFT 119 includes an island-shaped semiconductor film 132, which is anactive layer, and a gate electrode 104 including a lower-layer gateelectrode 104 a and an upper-layer gate electrode 104 b.

The gate electrodes 103 and 104 are electrically connected to the wordline W1. Note that each of TFT 120 and the TFT 121 shown in FIG. 10 hasthe same structure as that of any of the TFT 118 and the TFT 119, andgate electrodes of the TFTs 120 and 121 are electrically connected tothe word line W2.

One of a source region and a drain region of the TFT 118 and one of asource region and a drain region of the TFT 120 are electricallyconnected to the bit line 24 (which corresponds to a wiring 175).Further, one of a source region and a drain region of the TFT 119 andone of a source region and a drain region of the TFT 121 areelectrically connected to the bit line 25 (which corresponds to a wiring177).

The other of the source region and the drain region of each of the TFTs118 to 121 is electrically connected to the high voltage power supply 22through the wiring 27 (which corresponds to a wiring 176) or the wiring28 (which corresponds to a wiring 178) according to need. The storagestate of the mask ROM is determined depending on whether or not it iselectrically connected to the high voltage power supply 22.

As shown in FIG. 1, the TFT 118 is formed over a base film 153, which isformed over a substrate 151. The TFT 118 includes the island-shapedsemiconductor film 131, a gate insulating film 154, the gate electrode103 including the lower-layer gate electrode 103 a and the upper-layergate electrode 103 b, and sidewalls 171 a and 171 b. The island-shapedsemiconductor film 131 includes a region 163, which is one of the sourceregion and the drain region; a region 164, which is the other of thesource region and the drain region; low-concentration impurity regions162 a and 162 b; and a channel forming region 161.

The TFT 119 is formed over the base film 153, which is formed over thesubstrate 151. The TFT 119 includes the island-shaped semiconductor film132, the gate insulating film 154, the gate electrode 104 including thelower-layer gate electrode 104 a and the upper-layer gate electrode 104b, and sidewalls 191 a and 191 b. The island-shaped semiconductor film132 includes a region 184, which is one of the source region and thedrain region; a region 183, which is the other of the source region andthe drain region; low-concentration impurity regions 182 a and 182 b;and a channel forming region 181.

In FIG. 1, the base film 153 has one layer; however, the number oflayers may be determined as needed.

Over the TFTs 118 and 119, a first interlayer insulating film 155 isformed, and further, a second interlayer insulating film 156 is formedthereover.

Note that each of the TFTs 120 and 121 has a cross sectional structuresimilar to either of the TFT 118 or the TFT 119.

Over the second interlayer insulating film 156, an electrode 109 forelectrically connecting to the region 163, an electrode 113 forelectrically connecting to the region 164, an electrode 114 forelectrically connecting to the region 183, and an electrode 110 forelectrically connecting to the region 184 are formed. Each of theelectrode 109 and the electrode 113 serves as the source electrode orthe drain electrode of the TFT 118, and each of the electrode 114 andthe electrode 110 serves as the source electrode or the drain electrodeof the TFT 119.

Note that after formation of the electrode 110, the electrode 110 issoaked in an electrolyte while being applied with a voltage, therebybeing etched partially. Accordingly, the electrode 110 is notelectrically connected to the wiring 178 which is formed in a laterstep.

A third interlayer insulating film 135 is formed over the secondinterlayer insulating film 156, the electrode 109, the electrode 113,the electrode 114, and the electrode 110.

Over the third interlayer insulating film 135, the wiring 175 (whichcorresponds to the bit line 24), the wiring 177 (which corresponds tothe bit line 25), the wiring 176 (which corresponds to the wiring 27),and the wiring 178 (which corresponds to the wiring 28) are formed. Thewiring 175 (bit line 24) is electrically connected to the electrode 109,the wiring 177 (bit line 25) is electrically connected to the electrode114, and the wiring 176 (wiring 27) is connected to the electrode 114.Since the wiring 178 (wiring 28) is separated from the electrode 110 asdescribed above, the wiring 178 is not electrically connected to theelectrode 110.

FIG. 11 is a cross sectional view of a TFT of a logic circuit forcontrolling a mask ROM, and FIG. 12 is a circuit diagram of the logiccircuit. The basic configuration of the logic circuit is a CMOS circuitin which an n-channel TFT and a p-channel TFT are connectedcomplementarily. A column decoder and a row decoder to be describedlater are formed using such a CMOS circuit. FIG. 11 and FIG. 12 show aninverter using a CMOS circuit.

In FIG. 11 and FIG. 12, a gate electrode 443 and a gate electrode 444are formed using the same material and the same process. A wiring 407, awiring 404, and a wiring 405 are formed using the same material and thesame process. Further, a power supply line 431, a wiring 432, and apower supply line 433 are formed using the same material and the sameprocess. However, they may certainly be formed using different materialsand different processes according to need.

As shown in FIG. 11, an n-channel TFT 411 is formed over a base film 453which is formed over a substrate 451. The TFT 411 includes anisland-shaped semiconductor film 412 which is an active layer, a gateinsulating film 454, a gate electrode 443 including a lower-layer gateelectrode 443 a and an upper-layer gate electrode 443 b, and sidewalls471 a and 471 b. The base film 453 has one layer; however, the number oflayers may be determined as needed.

The island-shaped semiconductor film 412 includes a channel formingregion 461, low-concentration impurity regions 462 a and 462 b, a region463 which is one of the source region and the drain region, and a region464 which is the other of the source region and the drain region.

The region 463 which is one of the source region and the drain region ofthe TFT 411 is connected to the wiring 404, and the region 464 which isthe other of the source region and the drain region of the TFT 411 isconnected to the wiring 407.

A p-channel TFT 421 is formed over the base film 453 which is formedover the substrate 451. The TFT 421 includes an island-shapedsemiconductor film 422 which is an active layer, the gate insulatingfilm 454, a gate electrode 444 including a lower-layer gate electrode444 a and an upper-layer gate electrode 444 b, and sidewalls 491 a and491 b.

The island-shaped semiconductor film 422 includes a channel formingregion 481, a region 484 which is one of the source region and the drainregion, and a region 483 which is the other of the source region and thedrain region.

The region 484 which is one of the source region and the drain region ofthe TFT 421 is connected to the wiring 405, and the region 483 which isthe other of the source region and the drain region of the TFT 421 isconnected to the wiring 407.

In this embodiment mode, although a low concentration impurity region isnot formed in the p-channel TFT 421, it may be formed according to need.

The wiring 407 electrically connects the region 464 which is the otherof the source region and the drain region of the n-channel TFT 411 tothe region 483 which is the other of the source region and the drainregion of the p-channel TFT 421.

Over the TFTs 411 and 421, a first interlayer insulating film 455 and asecond interlayer insulating film 456 are formed.

The wiring 404, the wiring 405, and the wiring 407 are formed over thesecond interlayer insulating film 456, and the wiring 404 iselectrically connected to the region 463. The wiring 405 is electricallyconnected to the region 484. The wiring 407 is electrically connected tothe region 464 and the region 483.

A third interlayer insulating film 458 is formed over the secondinterlayer insulating film 456, the wiring 404, the wiring 405, and thewiring 407.

The power supply line 431 electrically connected to the wiring 404, thepower supply line 433 electrically connected to the wiring 405, and thewiring 432 electrically connected to the wiring 407 are formed over thethird interlayer insulating film 458. The wiring 432 serves as an outputterminal of the inverter. Further, a wiring 434 electrically connectedto the gate electrode 443 and the gate electrode 444 is formed, and thewiring 434 serves as an input terminal of the inverter.

The operation of the mask ROM using the present invention formed in theabove-described process will be described with reference to FIG. 10.Note that the circuit configuration and the operation are not limited tothe following descriptions as long as it is a circuit capable of readingindividual data such as an ID number that is stored in or written to amemory cell. Further, for simple description, FIG. 10 shows operation ofa memory cell for 2 bits, taking a 4-bit mask ROM as an example.However, the bit number and operation of the mask ROM is not limited tothis description, the present invention is applicable in the case of alarger number of bits, and data of a memory cell for all bits is readout.

As shown in FIG. 10, the mask ROM using the present invention includesthe column decoder 15, the row decoder 16, the memory cell array 11including the n-channel TFTs 118 to 121, the bit lines (data lines) 24and 25, the word lines W1 and W2, the high voltage power supply (VDD)22, the low voltage power supply (VSS or GND) 23, the column switchesSW1 to SW4, the address lines S1 and S2 which are controlled by thecolumn decoder 15, the output line 14, and the control line 17.

First, the operation of precharging a potential of the low voltage powersupply (VSS or GND) using a quarter of a reading time, in readingindividual data such as an ID number which is stored in or written to a1-bit memory cell, will be described.

The control line 17 is in a state of selecting the SW3 and the SW4 for aquarter of a reading time, and sends a signal for electricallyconnecting the bit lines (data lines) 24 and 25 to the low voltage powersupply (VSS or GND) 23. Thus, each of the bit lines (data lines) 24 and25 obtains a potential of the low voltage power supply (VSS or GND).

At this time, the word lines W1 and W2 are not in a state of selectingthe n-channel TFTs 118 to 121. Here, the selecting state indicates astate of electrically connecting a source terminal to a drain terminalof the n-channel TFTs 118 to 121.

The address lines S1 and S2, which are controlled by the column decoder15, are also not in a state of selecting the column switches SW1 andSW2. Here, the selecting state indicates a state of electricallyconnecting the bit lines (data lines) 24 and 25 to the output line 14.

Regarding a voltage to be precharged, depending on the circuitconfiguration, the system, the logic, or the like, there are variouscases such as a case of precharging a potential of the low voltage powersupply (VSS or GND) as the present invention, a case of precharging apotential of the high voltage power supply (VDD), and a case ofprecharging a potential of a generation voltage other than theforegoing, and there is no limitation. The most appropriate voltage maybe selected depending on the case.

Next, the operation of reading the individual data such as an ID numberfrom the mask ROM using the present invention, using the otherthree-fourths of the reading time, will be described. Here, in the casewhere a voltage having the same level as the high voltage power supply(VDD) is output, the read individual data such as an ID number isconsidered as High, and in the case where a voltage having the samelevel as the low voltage power supply (VSS or GND) is output, the readindividual data is considered as Low. Whether the read individual datasuch as the ID number is High or Low depends on the circuitconfiguration, the system, the logic, and the like, and not limited tothis description.

When the word line W1 is selected by the row decoder 16 and the addressline S1 is selected by the column decoder 15, the n-channel TFT 118 isselected. Then, the source terminal and the drain terminal of then-channel TFT 118 are electrically connected. That is, the bit line(data line) 24 and the high voltage power supply (VDD) 22, which are thesource terminal and the drain terminal of the n-channel TFT 118, areelectrically connected. The bit line is charged to a voltage which is athreshold amount of the n-channel TFT 118 lower than the voltage of thehigh voltage power supply (VDD) 22. Further, since the address line S1is selected by the column decoder 15, the bit line (data line) 24 andthe output line 14 are electrically connected. Here, since the bit lineis charged to a voltage which is a threshold amount of the n-channel TFT118 lower than the voltage of the high voltage power supply (VDD) 22,the output line 14 has the same potential as the bit line (data line)24. That is, a voltage which is a threshold amount of the n-channel TFT118 lower than the voltage of the high voltage power supply (VDD) 22 isoutput to the output line 14.

Although not shown, the voltage which is a threshold amount of then-channel TFT 118 lower than the voltage of the high voltage powersupply (VDD) 22 is made to pass through an amplifier, thereby apotential the same as that of the high voltage power supply (VDD) isoutput. Here, the amplifier is a circuit capable of increasing a voltageor a current, and may have a structure where two stages of inverters areconnected or a structure using a comparator or the like.

Thus, the High which is the individual data such as the ID number storedin or written to the n-channel TFT 118 is output to the output line 14.

Similarly, when the word line W1 is selected by the row decoder 16 andthe address line S2 is selected by the column decoder 15, the n-channelTFT 119 is selected. One terminal of the n-channel TFT 119 is notconnected to anywhere; however, by the above-described prechargingoperation, the bit line (data line) 25, which is the other terminal, hasa potential of the low voltage power supply 23 (VSS or GND). That is,the one terminal of the n-channel TFT 119 and the other terminal havealmost equal potentials to the potential of the low voltage power supply(VSS or GND) 23. Further, since the address line S2 is selected by thecolumn decoder 15, the bit line (data line) 25 and the output line 14are electrically connected. That is, a potential almost equal to that ofthe low voltage power supply (VSS or GND) 23 is output to the outputline 14.

Thus, the Low which is the individual data such as the ID number storedin or written to the n-channel TFT 119 is output to the output line 14.

In the above-described manner, the individual data such as the ID numberstored in or written to the mask ROM using the present invention can beread out.

A process for manufacturing a TFT of a memory cell array will bedescribed below with reference to FIGS. 5A to 5C, FIGS. 6A to 6C, FIGS.7A to 7C, FIGS. 8A and 8B, and FIGS. 9A and 9B.

First, as shown in FIG. 5A, a base film 153 is formed over a substrate151. As the substrate 151, a glass substrate of barium borosilicateglass, alumino borosilicate glass, or the like, a quartz substrate, astainless-steel substrate, an SOI (Silicon on Insulator) substrate whichis formed by formation of a single crystalline semiconductor layer on aninsulating surface, or the like can be used. Also, a substrate includinga synthetic resin having flexibility such as acrylic or plasticrepresented by poly(ethylene terephthalate) (PET), poly(ether sulfone)(PES), or poly(ethylene Naphthalate) (PEN) can be used. A case of usinga glass substrate as the substrate 151 will be described below.

The base film 153 is provided to prevent an alkali metal such as Na oran alkaline earth metal contained in the substrate 151 from diffusinginto a semiconductor film and causing an adverse effect on acharacteristic of a semiconductor element. Therefore, the base film 153is formed using an insulating film of silicon nitride, silicon oxidecontaining nitrogen, or the like which can suppress diffusion of thealkali metal or alkaline earth metal into the semiconductor film. Inthis embodiment mode, the base film 153 is formed by a plasma CVD methodby stacking a silicon oxide film and a silicon oxide film containingnitrogen so that thicknesses thereof are 10 to 100 nm (preferably 20 to70 μm, more preferably 50 nm) and 10 to 400 nm (preferably 50 to 300 nm,more preferably 100 nm), respectively.

Note that the base film 153 may be a single layer of an insulating filmcontaining silicon nitride, silicon oxide containing nitrogen, siliconnitride containing oxygen, or a stack of layers of a plurality ofinsulating films of silicon oxide, silicon nitride, silicon oxidecontaining nitrogen, silicon nitride containing oxygen, or the like.Further, in a case of using a substrate containing an alkali metal oralkaline earth metal in any amount such as a glass substrate, astainless-steel substrate, or a plastic substrate, it is effective toprovide a base film in terms of preventing diffusion of an impurity;however, if diffusion of an impurity is not much of a problem as in acase of using a quartz substrate, it is not always necessary to providea base film.

Next, a semiconductor film 101 is formed over the base film 153. Thethickness of the semiconductor film 101 is set at 25 to 100 nm(preferably, 30 to 80 nm). Note that the semiconductor film 101 may bean amorphous semiconductor or a polycrystalline semiconductor. Also,silicon germanium (SiGe) can be used as well as silicon (Si) as asemiconductor. In a case of using silicon germanium, the concentrationof germanium is preferably about 0.01 to 4.5 atomic %. In thisembodiment mode, an amorphous silicon film is formed to have a thicknessof 66 nm as the semiconductor film 101.

Next, a linear beam 111 is emitted to the semiconductor film 101 from alaser irradiation apparatus to carry out crystallization, as shown inFIG. 5B.

In the case of carrying out laser crystallization, the semiconductorfilm 101 may be subjected to heating treatment at 500° C. for one hourbefore laser crystallization, in order to increase resistance of thesemiconductor film 101 against a laser beam.

For the laser crystallization, a continuous wave laser or a pulsed laserwith a repetition rate of 10 MHz or more, preferably 80 MHz or more as apseudo CW laser can be used.

Specifically, the following and the like can be given as examples of thecontinuous wave laser: an Ar laser, a Kr laser, a CO₂ laser, a YAGlaser, a YVO₄ laser, a forsterite (Mg₂SiO₄) laser, a YLF laser, a YAlO₃laser, a GdVO₄ laser, a Y₂O₃ laser, an alexandrite laser, a Ti:sapphirelaser, a helium cadmium laser, and a laser of which a medium is apolycrystalline (ceramic) YAG, Y₂O₃, YVO₄, YAlO₃, or GdVO₄, added withone or more of Nd, Yb, Cr, Ti, Ho, Er, Tm, and Ta as a dopant.

Also, as the pseudo CW laser, a pulsed laser such as the following canbe used if pulse oscillation at a repetition rate of 10 MHz or more,preferably 80 MHz or more, is possible: an Ar laser, a Kr laser, anexcimer laser, a CO₂ laser, a YAG laser, a Y₂O₃ laser, a YVO₄ laser, aforsterite (Mg₂SiO₄) laser, a YLF laser, YAlO₃ laser, a GdVO₄ laser, analexandrite laser, a Ti:sapphire laser, a copper vapor laser, a goldvapor laser, or a laser of which a medium is a polycrystalline (ceramic)YAG, Y₂O₃, YVO₄, YAlO₃, or GdVO₄, added with one or more of Nd, Yb, Cr,Ti, Ho, Er, Tm, and Ta as a dopant.

Such a pulsed laser eventually exhibits an effect equivalent to that ofa continuous wave laser when the repetition rate is increased.

For example, in a case of using a solid-state laser capable ofcontinuous oscillation, a crystal with a large grain diameter can beobtained by irradiation with laser light of a second harmonic to afourth harmonic. Typically, it is desirable to use a second harmonic(532 nm) or a third harmonic (355 nm) of the YAG laser (fundamental waveof 1064 nm). For example, laser light emitted from a continuous wave YAGlaser is converted to a high harmonic by a nonlinear optical element,and emitted to the semiconductor film 604. The power density may beabout 0.01 to 100 MW/cm² (preferably 0.1 to 10 MW/cm²). Then,irradiation is carried out with a scanning speed of about 10 to 2000cm/sec.

Note that a laser of which a medium is a single-crystalline YAG, YVO₄,forsterite (Mg₂SiO₄), YAlO₃, or GdVO₄ doped with one or more of Nd, Yb,Cr, Ti, Ho, Er, Tm, and Ta as a dopant, or a polycrystalline (ceramic)YAG, Y₂O₃, YVO₄, YAlO₃, or GdVO₄, doped with one or more of Nd, Yb, Cr,Ti, Ho, Er, Tm, and Ta as a dopant; an Ar laser; a Kr laser; or aTi:sapphire laser is capable of continuous oscillation, and also capableof pulse oscillation by carrying out a Q switch operation, mode locking,or the like. When a laser beam is oscillated at a repetition rate of 10MHz or more, the semiconductor film is irradiated with a subsequentpulse while the semiconductor film is melted by a preceding laser andthen solidified. Consequently, since a solid-liquid interface in thesemiconductor film can be moved continuously unlike in a case of using apulsed laser with a low repetition rate, crystal grains thatcontinuously grow toward a scanning direction can be obtained.

When ceramics (polycrystals) are used for a medium, the medium can beformed into a free shape in a short amount of time and at low cost. Whensingle crystals are used, a column-shaped medium with several mm indiameter and several tens of mm long is usually used, but a largermedium can be formed when ceramic is used.

Since the concentration of a dopant such as Nd or Yb in the medium whichdirectly contributes to light emission cannot be changed significantlyin either single crystals or polycrystals, improvement in laser outputby increasing the concentration is limited to a certain extent. However,in the case of ceramics, there is a possibility that output can bedrastically improved since the size of the medium can be significantlyincreased compared to single crystals.

Further, in the case of ceramics, a medium having a parallelepiped shapeor a rectangular parallelepiped shape can be easily formed. When amedium having such a shape is used and oscillation light travels in azigzag in the medium, an oscillation light path can be longer.Accordingly, amplification is increased and oscillation with high outputbecomes possible. Since a laser beam emitted from the medium having sucha shape has a cross section of a quadrangular shape when being emitted,a linear beam can be easily shaped compared with the case of a circularbeam. The laser beam emitted in such a manner is shaped by using anoptical system; accordingly, a linear beam having a short side of lessthan or equal to 1 mm and a long side of several mm to several m can beeasily obtained. In addition, by uniformly irradiating the medium withexcited light, a linear beam has a uniform energy distribution in a longside direction.

By irradiation of the semiconductor film with this linear beam, theentire surface of the semiconductor film can be annealed more uniformly.In the case where uniform annealing is required from one end to theother end of the linear beam, slits may be provided for the ends so asto shield a portion where energy is attenuated from light.

By irradiating the semiconductor film 101 with laser light as mentionedabove, a crystalline semiconductor film 102 with improved crystallinityis formed.

Next, as shown in FIG. 5C, the crystalline semiconductor film 102 isused to form island-shaped semiconductor films 131 and 132. Theseisland-shaped semiconductor films 131 and 132 serve as active layers ofTFTs to be formed in a subsequent process.

In this embodiment mode, the case of using a glass substrate as thesubstrate 151 is described; however, in the case of using an SOIsubstrate as the substrate 151, a single-crystalline semiconductor layermay be formed into an island shape to serve as an active layer of a TFT.

Next, an impurity is introduced into the island-shaped semiconductorfilms 131 and 132 for controlling threshold voltages. In this embodimentmode, boron (B) is introduced into the island-shaped semiconductor films131 and 132 by doping of diborane (B₂H₆).

Next, a gate insulating film 154 is formed over the island-shapedsemiconductor films 131 and 132. For the gate insulating film 154,silicon oxide, silicon nitride, silicon oxide containing nitrogen, orthe like with a film thickness of 10 to 110 nm can be used, for example.Also, as a film formation method, a plasma CVD method, a sputteringmethod, or the like can be used. In this embodiment mode, the gateinsulating film 154 is formed using a silicon oxide film containingnitrogen that is formed by a plasma CVD method to have a film thicknessof 20 nm.

Next, a first conductive film 115 and a second conductive film 116 areformed over the gate insulating film 154 (FIG. 6A).

An element selected from tantalum (Ta), tungsten (W), titanium (Ti),molybdenum (Mo), or aluminum (Al); or an alloy material or compoundmaterial mainly containing the element as its main component may be usedfor the first conductive film 115 and the second conductive film 116.Alternatively, the conductive films may be formed using a semiconductorfilm typified by a polycrystalline silicon film doped with an impurityelement such as phosphorus (P).

In this embodiment mode, stacked films are formed using a tantalumnitride (TaN) film with a thickness of 10 to 50 nm, for example, 30 nm,which is formed as the first conductive film 115, and a tungsten (W)film with a thickness of 200 to 400 nm, for example, 370 nm, which isformed as the second conductive film 116.

Then, the first conductive film 115 and the second conductive film 116are etched so that lower-layer gate electrodes 103 a and 104 a areformed from the first conductive film 115 and upper-layer gateelectrodes 103 b and 104 b are formed from the second conductive film116. Accordingly, a gate electrode 103 including the lower-layer gateelectrode 103 a and the upper-layer gate electrode 103 b, and a gateelectrode 104 including the lower-layer gate electrode 104 a and theupper-layer gate electrode 104 b are formed (FIG. 6B). The gateelectrodes 103 and 104 may each be a single layer film instead ofstacked-layer films.

The gate electrodes 103 and 104 may be formed as a portion of a gatewiring. Alternatively, a gate wiring may be separately formed, and thenthe gate electrodes 103 and 104 may be connected to the gate wiring.

Next, an impurity imparting one conductivity type is added to theisland-shaped semiconductor films 131 and 132. As the impurity impartingone conductivity type, phosphorus (P) or arsenic (As) may be used whenusing an impurity imparting n-type conductivity. When using an impurityimparting p-type conductivity, boron (B) may be used.

In this embodiment mode, first, as a first adding step, an impurityimparting n-type conductivity is added to the island-shapedsemiconductor films 131 and 132 (FIG. 6C). Specifically, phosphorus (P)is introduced into the island-shaped semiconductor films 131 and 132using phosphine (PH₃), with an application voltage of 40 to 120 keV, anda dose amount of 1×10¹³ to 1×10¹⁵ cm². In this embodiment mode,phosphorus is added into the island-shaped semiconductor films 131 and132 using phosphine, with an application voltage of 60 keV and a doseamount of 2.6×10⁻¹³ cm⁻². In this manner, impurity regions 125 to 128are formed. Further, at the time of this introduction of the impurity,regions to be channel forming regions 161 and 181 are determined.

Then, insulating films, i.e. sidewalls 171 and 191, are formed so as tocover side surfaces of the gate electrodes 103 and 104, as shown in FIG.7A. In other words, the sidewalls 171 (171 a and 171 b) are formed onthe side surfaces of the gate electrode 103, and the sidewalls 191 (191a and 191 b) are formed on the side surfaces of the gate electrode 104.

The sidewalls 171 and 191 can be formed from an insulating filmincluding silicon by a plasma CVD method or a low pressure CVD (LPCVD)method. In this embodiment mode, taper-shaped sidewalls 171 and 191 areformed by formation of a silicon oxide film with a film thickness of 50to 200 nm, preferably 100 nm by a plasma CVD method, and etching of thesilicon oxide film. Alternatively, the sidewalls 171 and 191 may beformed using a silicon oxide film containing nitrogen.

Also, end portions of the sidewalls 171 and 191 need not necessarilyhave a taper shape, and they may have a rectangular shape.

Further, as a second adding step, phosphorus (P) is introduced into theisland-shaped semiconductor films 131 and 132 using phosphine (PH₃),with an application voltage of 10 to 50 keV, for example 20 keV, and adose amount of 5.0×10¹⁴ to 2.5×10¹⁶ cm⁻², for example 3.0×10¹⁵ cm⁻².

As the second adding step, using the gate electrode 103 and thesidewalls 171 as masks, phosphorus is introduced into the island-shapedsemiconductor film 131; accordingly, a region 163, which is one of asource region and a drain region, a region 164 which is the other of thesource region and the drain region, and low-concentration impurityregions 162 a and 162 b are formed in the island-shaped semiconductorfilm 131. Similarly, using the gate electrode 104 and the sidewalls 191as masks, phosphorus is introduced into the island-shaped semiconductorfilm 132, and a region 183, which is one of a source region and a drainregion, a region 184, which is the other of the source region and thedrain region, and low-concentration impurity regions 182 a and 182 b areformed in the island-shaped semiconductor film 132.

In this embodiment mode, phosphorus (P) is included in the regions 163and 164, which are the source region and the drain region of ann-channel TFT 118, and the regions 183 and 184, which are the sourceregion and the drain region of an n-channel TFT 119, at a concentrationof 1×10¹⁹ to 5×10²¹ cm⁻³.

Also, phosphorus (P) is included at a concentration of 1×10¹⁸ to 5×10¹⁹cm⁻³ in the low-concentration impurity regions 162 a and 162 b of then-channel TFT 118 and the low-concentration impurity regions 182 a and182 b of the n-channel TFT 119.

Next, a first interlayer insulating film 155 is formed so as to coverthe island-shaped semiconductor films 131 and 132, the gate insulatingfilm 152, the gate electrodes 103 and 104, and the sidewalls 171 and 191(FIG. 7C).

As the first interlayer insulating film 155, an insulating filmcontaining silicon, for example, a silicon oxide film, a silicon nitridefilm, or a silicon oxide film containing nitrogen, or a stacked filmthereof is formed by a plasma CVD method or a sputtering method. Ofcourse, the first interlayer insulating film 155 is not limited to thesilicon oxide film containing nitrogen, the silicon nitride film, or thestacked film thereof, and other insulating film containing silicon maybe used in a single-layer or stacked-layer structure.

In this embodiment mode, a silicon oxide film containing nitrogen isformed to have a thickness of 50 nm by a plasma CVD method, and animpurity is activated by a laser irradiation method. Alternatively,after forming the silicon oxide film containing nitrogen, the impuritymay be activated by heating in a nitrogen atmosphere at 550° C. for fourhours.

Next, a silicon nitride film is formed to have a thickness of 100 nm bya plasma CVD method, and a silicon oxide film is additionally formed tohave a thickness of 600 nm. These stacked layers of the silicon oxidefilm containing nitrogen, the silicon nitride film, and the siliconoxide film are the first interlayer insulating film 155.

Then, the entire substrate is heated at 410° C. for one hour, andhydrogenation is carried out by releasing hydrogen from the siliconnitride film.

Next, a second interlayer insulating film 156 is formed so as to coverthe first interlayer insulating film 155.

For the second interlayer insulating film 156, an inorganic materialsuch as an oxide of silicon or nitride of silicon can be used by using aCVD method, a sputtering method, an SOG (Spin On Glass) method, or thelike. In this embodiment mode, a silicon oxide film is formed as thesecond interlayer insulating film 156.

An insulating film using siloxane may be formed as the second interlayerinsulating film 156. The siloxane has a skeletal structure including abond of silicon (Si) and oxygen (O), and an organic group containing atleast hydrogen (for example, an alkyl group or aromatic hydrocarbon) isused for a substituent. Alternatively, a fluoro group may be used forthe substituent. Further, the organic group containing at least hydrogenand the fluoro group may be used for the substituent.

A passivation film may be formed over the second interlayer insulatingfilm 156. As the passivation film, a film that does not easily allowpenetration of moisture, oxygen, and the like compared to otherinsulating films may be formed. Typically, a silicon nitride film, asilicon oxide film, a silicon nitride film containing oxygen, a siliconoxide film containing nitrogen, a thin film mainly containing carbon(for example, a diamong-like carbon (DLC) film or a carbon nitride (CN)film), or the like which is obtained by a sputtering method or a CVDmethod, can be used.

Then, over the second interlayer insulating film 156, a conductive filmis formed, and using the conductive film, electrodes 109, 113, 114, and110, which are to be source electrodes and drain electrodes, are formed(FIG. 8A).

The electrode 109, which is one of the source electrode and the drainelectrode of the TFT 118, is electrically connected to the region 163,and the electrode 113, which is the other of the source electrode andthe drain electrode, is electrically connected to the region 164. Theelectrode 114, which is one of the source electrode and the drainelectrode of the TFT 119, is electrically connected to the region 183,and the electrode 110, which is the other of the source electrode andthe drain electrode, is electrically connected to the region 184.

In this embodiment mode, the electrodes 109, 113, 114, and 110 areformed by a CVD method, a sputtering method, or the like using anelement such as aluminum (Al), tungsten (W), titanium (Ti), tantalum(Ta), molybdenum (Mo), nickel (Ni), cobalt (Co), iron (Fe), platinum(Pt), copper (Cu), gold (Au), silver (Ag), manganese (Mn), neodymium(Nd), carbon (C), or silicon (Si), or an alloy material or a compoundmaterial containing the above element as its main component, with asingle layer structure or a stacked structure. An alloy materialcontaining aluminum as its main component corresponds to, for example, amaterial containing nickel, whose main component is aluminum, or analloy material containing nickel and one or both of carbon and silicon,whose main component is aluminum. For the electrodes 109, 113, 114, and110, for example, a stacked structure of a barrier film, analuminum-silicon (Al—Si) film, and a barrier film, or a stackedstructure of a barrier film, an aluminum-silicon (Al—Si) film, atitanium nitride (TiN) film, and a barrier film may be preferablyemployed. It is to be noted that the barrier film corresponds to a thinfilm formed using titanium, a nitride of titanium, molybdenum, or anitride of molybdenum. Aluminum and aluminum silicon which have a lowresistance and are inexpensive are optimal materials for forming theelectrodes 109, 113, 114, and 110. In addition, an aluminum alloy filmcan prevent interdiffusion between silicon and aluminum even when beingin contact with silicon. In addition, generation of a hillock ofaluminum or aluminum silicon can be prevented when upper and lowerbarrier layers are provided.

In this embodiment mode, the electrodes 109, 113, 114, and 110 areformed using stack layers of a titanium (Ti) film, a titanium nitridefilm, an aluminum (Al) film, and a titanium (Ti) film, which are 60 nm,50 nm, 500 nm, and 100 nm, respectively.

The electrodes 109, 113, 114, and 110 may be formed by using the samematerial and the same process as those of a wiring, or the electrodesand the wiring may be separately formed and then may be connected.

Next, a third interlayer insulating film 135 is formed over theelectrode 109, the electrode 113, the electrode 114, the electrode 110,and the second interlayer insulating film 156 or over a passivation filmin the case where the passivation film is formed (FIG. 8B). The thirdinterlayer insulating film 135 may be formed of a similar material tothat of the second interlayer insulating film 156.

A contact hole 165 reaching the electrode 109, a contact hole 166reaching the electrode 113, a contact hole 167 reaching the electrode114, and a contact hole 168 reaching the electrode 110 are formed in thethird interlayer insulating film 135 (FIG. 9A).

Then, the whole substrate is soaked in an electrolyte. The electrolytemay be an electrolyte capable of dissolving the material of theelectrode 109, the electrode 113, the electrode 114, and the electrode110. For example, in the case where aluminum is used as the material ofthe electrode 109, the electrode 113, the electrode 114, and theelectrode 110, potassium hydroxide or phosphate can be used as theelectrolyte. Note that the object soaked in the electrolyte does notneed to be the whole substrate as long as the electrode can bedissolved.

Examples of combinations of the material for forming the electrode 109,the electrode 113, the electrode 114, and the electrode 110 and theelectrolyte are shown in Table 1.

TABLE 1 Current Voltage density Temperature Metal (V) (A/dm²)Electrolyte (° C.) Aluminum 30-70 30-200 Potassium 80 hydroxide Aluminum10-40 10-100 Phosphate 60 Nickel 40 30-60  Sulfuric acid 40 Copper1.5-2  1-10 Phosphate• Room Chromic acid temperature Silver 2-4 0.5-3  Potassium Room ferrocyanide temperature

When the electrode 110 is soaked in the electrolyte and is applied witha voltage, metal on a surface of the electrode dissociates as ions intothe electrolyte, so that the electrode material is dissolved. As shownin FIG. 9B, a part of the electrode 110 is dissolved so that aseparation region 169 is formed. Note that it is preferable that the TFT119 be a normally-off type TFT at this time to prevent the electrode 109from being dissolved. Further, the contact hole 165 reaching theelectrode 109 may be formed after the separation region 169 is formed.

Then, as shown in FIG. 1, a wiring 175 electrically connected to theelectrode 109, a wiring 176 electrically connected to the electrode 113,and a wiring 177 electrically connected to the electrode 114 are formedover the third interlayer insulating film 135.

A wiring 178 is formed over the electrode 110 and the third interlayerinsulating film 135. Since the wiring 178 is formed so as to reach theseparation region 169, the wiring 178 is not electrically connected tothe electrode 110.

The wirings 175 to 178 may be formed of any of the materials for formingthe electrode 109 and the like.

In the above-described manner, TFTs of a memory cell array is formed.Note that TFTs of a logic circuit may be formed similarly to the TFTs ofthe memory cell array, or may be formed over another substrate,separated, and then be electrically connected to the TFTs of the memorycell array.

According to the present invention, memory cells of mask ROMs havingdata of different ID numbers can be easily formed. Therefore, reductionof manufacturing time and manufacturing cost of a semiconductor devicecapable of wireless communication that uses an IC can be realized.

FIG. 13 is a top view of a mask ROM including a memory cell arrayaccording to the present invention. A memory cell array 920(corresponding to a memory cell array 11 in FIG. 10) of the presentinvention is formed in a mask ROM 900, and with the use of theabove-described TFTs of a logic circuit, a column decoder 921 (a columndecoder 15 in FIG. 10) and a row decoder 922 (corresponding to a columndecoder 16 in FIG. 10) are formed.

FIG. 14 shows an example of a semiconductor device capable of wirelesscommunication that uses an IC, which includes the mask ROM 900 of FIG.13. The semiconductor device shown in FIG. 14 is only an example, andthe present invention is not limited to the structure shown in FIG. 14.

A semiconductor device (also referred to as an ID chip, an IC chip, anIC tag, an ID tag, a wireless chip, or an RFID) 931 shown in FIG. 14includes circuit blocks of an antenna 917, a high-frequency circuit 914,a power supply circuit 915, a reset circuit 911, a rectifier circuit906, a demodulation circuit 907, an analog amplifier 908, a clockgeneration circuit 903, a modulation circuit 909, a signal outputcontrol circuit 901, a CRC circuit 902, a mask ROM 900, a codeextraction circuit 904, and a code identification circuit 905. The powersupply circuit 915 includes circuit blocks of a rectifier circuit and astorage capacitor. Further, as shown in FIG. 13, the mask ROM 900includes the memory cell array 920, the column decoder 921, and the rowdecoder 922.

In the step of forming the separation region 169 by dissolving theelectrode 110 shown in FIG. 9B, a circuit 951 and a computer 955 shownin FIG. 15 are connected to the memory cell array 920. The circuit 951may be formed over the same substrate as that of the memory cell array920 or may be externally attached.

TFTs corresponding to TFTs of the memory cell array 920 are formed inthe circuit 951. The circuit 951 can selectively apply a desired voltageto an individual wiring (electrode) in the memory cell array 920 inaccordance with a signal from the computer 955. With this voltageapplied, the substrate is soaked in an electrolyte. The voltage in acondition of dissolving the wiring, which is set in consideration of theelectrolyte and a wiring material, is applied to the wiring, therebydissolving the wiring of an opening portion in the electrolyte. Thus,individual wirings (electrodes) over a surface of the substrate areselectively separated.

In order to secure space over a surface of the substrate, a part of thecircuit 951 which is connected to the computer 955 and reaches theopening portion may be formed on a rear surface of the substrate. Inthis case, an opening portion reaching the rear surface from the surfaceis formed in the substrate, and a wiring is formed in the openingportion so as to penetrate through the substrate.

By the present invention, different individual data such as ID numberscan be easily given to individual semiconductor devices capable ofwireless communication that use ICs. In particular, in manufacturing alarge number of semiconductor devices capable of wireless communicationover a large-area substrate, tact and cost can be reduced.

This embodiment mode can be implemented in combination with descriptionin any of the other embodiment modes and embodiments as needed.

Embodiment Mode 2

In Embodiment Mode 2, a manufacturing process of TFTs of a memory cellarray and TFTs of a logic circuit over the same substrate will bedescribed with reference to FIGS. 16A to 16D, FIGS. 17A to 17C, FIGS.18A to 18C, FIGS. 19A and 19B, and FIGS. 20A and 20B.

First, as shown in FIG. 16A, a base film 602 is formed over a substrate601. As the substrate 601, a glass substrate of barium borosilicateglass, alumino borosilicate glass, or the like, a quartz substrate, astainless-steel substrate, an SOI (Silicon on Insulator) substrate whichis formed by formation of a single crystalline semiconductor layer on aninsulating surface, or the like can be used. Also, a substrate includinga synthetic resin having flexibility such as acrylic or plasticrepresented by poly(ethylene terephthalate) (PET), poly(ether sulfone)(PES), or poly(ethylene Naphthalate) (PEN) can be used. A case of usinga glass substrate as the substrate 601 will be described below.

The base film 602 is provided to prevent an alkali metal such as Na oran alkaline earth metal contained in the substrate 601 from diffusinginto a semiconductor film and causing an adverse effect on acharacteristic of a semiconductor element. Therefore, the base film 602is formed using an insulating film of silicon nitride, silicon oxidecontaining nitrogen, or the like which can suppress diffusion of thealkali metal or alkaline earth metal into the semiconductor film. Inthis embodiment mode, the base film 602 is formed by a plasma CVD methodby stacking a silicon oxide film and a silicon oxide film containingnitrogen so that thicknesses thereof are 10 to 100 nm (preferably 20 to70 nm, more preferably 50 nm) and 10 to 400 nm (preferably 50 to 300 nm,more preferably 100 nm), respectively.

Note that the base film 602 may be a single layer of an insulating filmcontaining silicon nitride, silicon oxide containing nitrogen, siliconnitride containing oxygen, or a stack of layers of a plurality ofinsulating films of silicon oxide, silicon nitride, silicon oxidecontaining nitrogen, silicon nitride containing oxygen, or the like.Further, in a case of using a substrate containing an alkali metal oralkaline earth metal in any amount such as a glass substrate, astainless-steel substrate, or a plastic substrate, it is effective toprovide a base film in terms of preventing diffusion of an impurity;however, if diffusion of an impurity is not much of a problem as in acase of using a quartz substrate, it is not always necessary to providea base film.

Next, a semiconductor film 604 is formed over the base film 602. Thethickness of the semiconductor film 604 is set at 25 to 100 nm(preferably, 30 to 80 nm). Note that the semiconductor film 604 may bean amorphous semiconductor or a polycrystalline semiconductor. Also,silicon germanium (SiGe) can be used as well as silicon (Si) as asemiconductor. In a case of using silicon germanium, the concentrationof germanium is preferably about 0.01 to 4.5 atomic %. In thisembodiment mode, an amorphous silicon film is formed to have a thicknessof 66 nm as the semiconductor film 604.

Next, a linear beam 603 is emitted to the semiconductor film 604 from alaser irradiation apparatus to carry out crystallization, as shown inFIG. 16B.

In the case of carrying out laser crystallization, the semiconductorfilm 604 may be subjected to heating treatment at 500° C. for one hourbefore laser crystallization, in order to increase resistance of thesemiconductor film 604 against a laser beam.

For the laser crystallization, a continuous wave laser or a pulsed laserwith a repetition rate of 10 MHz or more, preferably 80 MHz or more as apseudo CW laser can be used.

Specifically, the following and the like can be given as examples of thecontinuous wave laser: an Ar laser, a Kr laser, a CO₂ laser, a YAGlaser, a YVO₄ laser, a forsterite (Mg₂SiO₄) laser, a YLF laser, a YAlO₃laser, a GdVO₄ laser, a Y₂O₃ laser, an alexandrite laser, a Ti:sapphirelaser, a helium cadmium laser, and a laser of which a medium is apolycrystalline (ceramic) YAG, Y₂O₃, YVO₄, YAlO₃, or GdVO₄, added withone or more of Nd, Yb, Cr, Ti, Ho, Er, Tm, and Ta as a dopant.

Also, as the pseudo CW laser, a pulsed laser such as the following canbe used if pulse oscillation at a repetition rate of 10 MHz or more,preferably 80 MHz or more, is possible: an Ar laser, a Kr laser, anexcimer laser, a CO₂ laser, a YAG laser, a Y₂O₃ laser, a YVO₄ laser, aforsterite (Mg₂SiO₄) laser, a YLF laser, YAlO₃ laser, a GdVO₄ laser, analexandrite laser, a Ti:sapphire laser, a copper vapor laser, a goldvapor laser, or a laser of which a medium is a polycrystalline (ceramic)YAG, Y₂O₃, YVO₄, YAlO₃, or GdVO₄, added with one or more of Nd, Yb, Cr,Ti, Ho, Er, Tm, and Ta as a dopant.

Such a pulsed laser eventually exhibits an effect equivalent to that ofa continuous wave laser when the repetition rate is increased.

For example, in a case of using a solid-state laser capable ofcontinuous oscillation, a crystal with a large grain diameter can beobtained by irradiation with laser light of a second harmonic to afourth harmonic. Typically, it is desirable to use a second harmonic(532 nm) or a third harmonic (355 nm) of the YAG laser (fundamental waveof 1064 nm). For example, laser light emitted from a continuous wave YAGlaser is converted to a high harmonic by a nonlinear optical element,and emitted to the semiconductor film 604. The power density may beabout 0.01 to 100 MW/cm² (preferably 0.1 to 10 MW/cm²). Then,irradiation is carried out with a scanning speed of about 10 to 2000cm/sec.

Note that a laser of which a medium is a single-crystalline YAG, YVO₄,forsterite (Mg₂SiO₄), YAlO₃, or GdVO₄ doped with one or more of Nd, Yb,Cr, Ti, Ho, Er, Tm, and Ta as a dopant, or a polycrystalline (ceramic)YAG, Y₂O₃, YVO₄, YAlO₃, or GdVO₄, doped with one or more of Nd, Yb, Cr,Ti, Ho, Er, Tm, and Ta as a dopant; an Ar laser; a Kr laser; or aTi:sapphire laser is capable of continuous oscillation, and also capableof pulse oscillation by carrying out a Q switch operation, mode locking,or the like. When a laser beam is oscillated at a repetition rate of 10MHz or more, the semiconductor film is irradiated with a subsequentpulse while the semiconductor film is melted by a preceding laser andthen solidified. Consequently, since a solid-liquid interface in thesemiconductor film can be moved continuously unlike in a case of using apulsed laser with a low repetition rate, crystal grains thatcontinuously grow toward a scanning direction can be obtained.

When ceramics (polycrystals) are used for a medium, the medium can beformed into a free shape in a short amount of time and at low cost. Whensingle crystals are used, a column-shaped medium with several mm indiameter and several tens of mm long is usually used, but a largermedium can be formed when ceramic is used.

Since the concentration of a dopant such as Nd or Yb in the medium whichdirectly contributes to light emission cannot be changed significantlyin either single crystals or polycrystals, improvement in laser outputby increasing the concentration is limited to a certain extent. However,in the case of ceramics, there is a possibility that output can bedrastically improved since the size of the medium can be significantlyincreased compared to single crystals.

Further, in the case of ceramics, a medium having a parallelepiped shapeor a rectangular parallelepiped shape can be easily formed. When amedium having such a shape is used and oscillation light travels in azigzag in the medium, an oscillation light path can be longer.Accordingly, amplification is increased and oscillation with high outputbecomes possible. Since a laser beam emitted from the medium having sucha shape has a cross section of a quadrangular shape when being emitted,a linear beam can be easily shaped compared with the case of a circularbeam. The laser beam emitted in such a manner is shaped by using anoptical system; accordingly, a linear beam having a short side of lessthan or equal to 1 mm and a long side of several mm to several m can beeasily obtained. In addition, by uniformly irradiating the medium withexcited light, a linear beam has a uniform energy distribution in a longside direction.

By irradiation of the semiconductor film with this linear beam, theentire surface of the semiconductor film can be annealed more uniformly.In the case where uniform annealing is required from one end to theother end of the linear beam, slits may be provided for the ends so asto shield a portion where energy is attenuated from light.

By irradiating the semiconductor film 604 with laser light as mentionedabove, a crystalline semiconductor film 605 with improved crystallinityis formed.

Next, as shown in FIG. 16C, the crystalline semiconductor film 605 isused to form island-shaped semiconductor films 611 to 614. Theseisland-shaped semiconductor films 611 to 614 serve as active layers ofTFTs to be formed in a subsequent process.

In this embodiment mode, the case of using a glass substrate as thesubstrate 601 is described; however, in the case of using an SOIsubstrate as the substrate 601, a single-crystalline semiconductor layermay be formed into an island shape to serve as an active layer of a TFT.

Next, an impurity is introduced into the island-shaped semiconductorfilms 611 to 614 for controlling threshold voltages. In this embodimentmode, boron (B) is introduced into the island-shaped semiconductor films611 to 614 by doping of diborane (B₂H₆).

Next, a gate insulating film 615 is formed over the island-shapedsemiconductor films 611 to 614. For the gate insulating film 615,silicon oxide, silicon nitride, silicon oxide containing nitrogen, orthe like with a film thickness of 10 to 110 nm can be used, for example.Also, as a film formation method, a plasma CVD method, a sputteringmethod, or the like can be used. In this embodiment mode, the gateinsulating film 615 is formed using a silicon oxide film containingnitrogen that is formed by a plasma CVD method to have a film thicknessof 20 nm.

Then, after forming a conductive film over the gate insulating film 615,gate electrodes 621 to 624 are formed using the conductive film.

The gate electrodes 621 to 624 are formed to have a structure with asingle layer of a conductive film, or a structure in which two or morelayers of conductive films are stacked. In the case where two or moreconductive films are stacked, the gate electrodes 621 to 624 may beformed by stacking layers of an element selected from tantalum (Ta),tungsten (W), titanium (Ti), molybdenum (Mo), or aluminum (Al); or analloy material or compound material mainly containing the element.Alternatively, the gate electrodes may be formed using a semiconductorfilm typified by a polycrystalline silicon film doped with an impurityelement such as phosphorus (P). In this embodiment mode, the gateelectrodes 621 to 624 are formed using a tantalum nitride (TaN) filmwith a thickness of 10 to 50 nm, for example, 30 nm, which is formed aslower-layer gate electrodes 621 a to 624 a, and a tungsten (W) film witha thickness of 200 to 400 nm, for example, 370 μm, which is formed asupper-layer gate electrodes 621 b to 624 b.

The gate electrodes 621 to 624 may be formed as a portion of a gatewiring. Alternatively, a gate wiring may be separately formed, and thenthe gate electrodes 621 to 624 may be connected to the gate wiring.

Next, an impurity imparting one conductivity type is added to theisland-shaped semiconductor films 611 to 613. In this adding step, theisland-shaped semiconductor film 614 and the gate electrode 624, i.e. aregion to be a p-channel TFT 694, is covered with a resist 618, and theimpurity imparting one conductivity type is not added to theisland-shaped semiconductor film 614.

As the impurity imparting one conductivity type, phosphorus (P) orarsenic (As) may be used when using an impurity imparting n-typeconductivity. When using an impurity imparting p-type conductivity,boron (B) may be used.

In this embodiment mode, first, as a first adding step, an impurityimparting n-type conductivity is added to the island-shapedsemiconductor films 611 to 613 (FIG. 16D). Specifically, phosphorus (P)is introduced into the island-shaped semiconductor films 611 to 613using phosphine (PH₃), with an application voltage of 40 to 120 keV, anda dose amount of 1×10¹³ to 1×10¹⁵ cm⁻². In this embodiment mode,phosphorus is added into the island-shaped semiconductor films 611 to613 using phosphine, with an application voltage of 60 keV and a doseamount of 2.6×10¹³ cm⁻². At the time of this introduction of theimpurity, regions to be channel forming regions 631, 641, and 651 aredetermined.

Then, insulating films, i.e. sidewalls 626 to 629, are formed so as tocover side surfaces of the gate electrodes 621 to 624, as shown in FIG.17A. In other words, the sidewalls 626 (626 a and 626 b) are formed onthe side surfaces of the gate electrode 621, the sidewalls 627 (627 aand 627 b) are formed on the side surfaces of the gate electrode 622,the sidewalls 628 (628 a and 628 b) are formed on the side surfaces ofthe gate electrode 623, and the sidewalls 629 (629 a and 629 b) areformed on the side surfaces of the gate electrode 624.

The sidewalls 626 to 629 can be formed from an insulating film includingsilicon by a plasma CVD method or a low pressure CVD (LPCVD) method. Inthis embodiment mode, taper-shaped sidewalls 626 to 629 are formed byformation of a silicon oxide film with a film thickness of 50 to 200 nm,preferably 100 nm by a plasma CVD method, and etching of the siliconoxide film. Alternatively, the sidewalls 626 to 629 may be formed usinga silicon oxide film containing nitrogen.

Also, end portions of the sidewalls 626 to 629 need not necessarily havea taper shape, and they may have a rectangular shape.

Next, as shown in FIG. 17B, a resist 616 is formed to cover theisland-shaped semiconductor film 614, the gate electrode 624, and thesidewalls 629, which are a region later to be the p-channel TFT 694.

Further, as a second adding step, phosphorus (P) is introduced into theisland-shaped semiconductor films 611 to 613 using phosphine (PH₃), withan application voltage of 10 to 50 keV, for example 20 keV, and a doseamount of 5.0×10¹⁴ to 2.5×10¹⁶ cm⁻², for example 3.0×10¹⁵ cm⁻².

As the second adding step, using the gate electrode 621 and thesidewalls 626 as masks, phosphorus is introduced into the island-shapedsemiconductor film 611; accordingly, a region 633, which is one of asource region and a drain region, a region 634 which is the other of thesource-region and the drain region, and low-concentration impurityregions 632 a and 632 b are formed in the island-shaped semiconductorfilm 611. Similarly, using the gate electrode 622 and the sidewalls 627as masks, phosphorus is introduced into the island-shaped semiconductorfilm 612, and a region 643, which is one of a source region and a drainregion, a region 644, which is the other of the source region and thedrain region, and low-concentration impurity regions 642 a and 642 b areformed in the island-shaped semiconductor film 612. Further, using thegate electrode 623 and the sidewalls 628 as masks, phosphorus isintroduced into the island-shaped semiconductor film 613, and a region653, which is one of a source region and a drain region, a region 654,which is the other of the source region and the drain region, andlow-concentration impurity regions 652 a and 652 b are formed in theisland-shaped semiconductor film 613.

In this embodiment mode, phosphorus (P) is included in the regions 633and 634, which are the source region and the drain region of ann-channel TFT 691, the regions 643 and 644, which are the source regionand the drain region of an n-channel TFT 692, and the regions 653 and654, which are the source region and the drain region of an n-channelTFT 693, at a concentration of 1×10¹⁹ to 5×10²¹ cm⁻³.

Also, phosphorus (P) is included at a concentration of 1×10¹⁸ to 5×10¹⁹cm⁻³ in the low-concentration impurity regions 632 a and 632 b of then-channel TFT 691, the low-concentration impurity regions 642 a and 642b of the n-channel TFT 692, and the low-concentration impurity regions652 a and 652 b of the n-channel TFT 693.

Then, the resist 616 is removed, and a resist 617 is formed covering theisland-shaped semiconductor films 611 to 613, the gate electrodes 621 to623, and the sidewalls 626 to 628, that is a region to be the n-channelTFTs 691 to 693.

In order to form the p-channel TFT 694, an impurity imparting theopposite conductivity type to the above-described impurity imparting oneconductivity type, that is an impurity imparting p-type conductivity isadded to the island-shaped semiconductor film 614. Specifically, usingdiborane (B₂H₆), boron (B) is introduced into the island-shapedsemiconductor film 614 under a condition in which an application voltageis 60 to 100 keV, for example, 80 keV, and a dose amount is 1×10¹³ to5×10¹⁵ cm⁻², for example, 3×10¹⁵ cm⁻². Consequently, regions 663 and 664which are a source region and a drain region of the p-channel TFT areformed, and in addition, a channel forming region 661 is formed withthis introduction of the impurity (FIG. 17C).

Note that with regard to introduction of boron into the p-channel TFT694, since application voltage is high, a sufficient amount of boron forforming the region 663 and the region 664 is added to the island-shapedsemiconductor film 614 even through the sidewalls 629 and the gateinsulating film 615.

In the regions 663 and 664 which are the source region and the drainregion of the p-channel TFT 694, boron (B) is included at aconcentration of 1×10¹⁹ to 5×10²¹ cm⁻³.

Next, the resist 617 is removed, and a first interlayer insulating film671 is formed so as to cover the island-shaped semiconductor films 611to 614, the gate insulating film 615, the gate electrodes 621 to 624,and the sidewalls 626 to 629.

As the first interlayer insulating film 671, an insulating filmcontaining silicon, for example, a silicon oxide film, a silicon nitridefilm, or a silicon oxide film containing nitrogen, or a stacked filmthereof is formed by a plasma CVD method or a sputtering method. Ofcourse, the first interlayer insulating film 671 is not limited to thesilicon oxide film containing nitrogen, the silicon nitride film, or thestacked film thereof, and other insulating film containing silicon maybe used in a single-layer or stacked-layer structure.

In this embodiment mode, a silicon oxide film containing nitrogen isformed to have a thickness of 50 nm by a plasma CVD method, and animpurity is activated by a laser irradiation method. Alternatively,after forming the silicon oxide film containing nitrogen, the impuritymay be activated by heating in a nitrogen atmosphere at 550° C. for fourhours.

Next, a silicon nitride film is formed to have a thickness of 100 nm bya plasma CVD method, and a silicon oxide film is additionally formed tohave a thickness of 600 nm. These stacked layers of the silicon oxidefilm containing nitrogen, the silicon nitride film, and the siliconoxide film are the first interlayer insulating film 671.

Then, the entire substrate is heated at 410° C. for one hour, andhydrogenation is carried out by releasing hydrogen from the siliconnitride film.

Next, a second interlayer insulating film 672 is formed so as to coverthe first interlayer insulating film 671 (FIG. 18A).

For the second interlayer insulating film 672, an inorganic materialsuch as an oxide of silicon or nitride of silicon can be used by using aCVD method, a sputtering method, an SOG (Spin On Glass) method, or thelike. In this embodiment mode, a silicon oxide film is formed as thesecond interlayer insulating film 672.

An insulating film using siloxane may be formed as the second interlayerinsulating film 672. The siloxane has a skeletal structure including abond of silicon (Si) and oxygen (O), and an organic group containing atleast hydrogen (for example, an alkyl group or aromatic hydrocarbon) isused for a substituent. Alternatively, a fluoro group may be used forthe substituent. Further, the organic group containing at least hydrogenand the fluoro group may be used for the substituent.

A third interlayer insulating film may be formed over the secondinterlayer insulating film 672. As the third interlayer insulating film,a film that does not easily allow penetration of moisture, oxygen, andthe like compared to other insulating films may be formed. Typically, asilicon nitride film, a silicon oxide film, a silicon nitride filmcontaining oxygen, a silicon oxide film containing nitrogen, a thin filmmainly containing carbon (for example, a diamong-like carbon (DLC) filmor a carbon nitride (CN) film), or the like which is obtained by asputtering method or a CVD method, can be used.

Next, contact holes for electrical connection to the island-shapedsemiconductor films 611, 612, 613, and 614 are formed in the interlayerinsulating films 671 and 672.

In the interlayer insulating films 671 and 672, a contact hole 673reaching the region 633 of the island-shaped semiconductor film 611, acontact hole 674 reaching the region 634 of the island-shapedsemiconductor film 611, a contact hole 675 reaching the region 643 ofthe island-shaped semiconductor film 612, a contact hole 676 reachingthe region 644 of the island-shaped semiconductor film 612, a contacthole 677 reaching the region 653 of the island-shaped semiconductor film613, a contact hole 678 reaching the region 654 of the island-shapedsemiconductor film 613, a contact hole 679 reaching the region 663 ofthe island-shaped semiconductor film 614, and a contact hole 680reaching the region 664 of the island-shaped semiconductor film 614 areformed (FIG. 18B).

Note that the contact holes 673 to 680 may each include either onecontact hole or a plurality of contact holes.

Then, over the second interlayer insulating film 672, a conductive filmis formed, and using the conductive film, source electrodes and drainelectrodes 681, 682, 683, 684, 685, 686, and 687 are formed (FIG. 18C).

The electrode 681, which is one of the source electrode and the drainelectrode of the TFT 691, is electrically connected to the region 633,and the electrode 682, which is the other of the source electrode andthe drain electrode, is electrically connected to the region 634. Theelectrode 683, which is one of the source electrode and the drainelectrode of the TFT 692, is electrically connected to the region 643.The electrode 684, which is the other of the source electrode and thedrain electrode, is electrically connected to the region 644.

The electrode 685, which is one of the source electrode and the drainelectrode of the TFT 693, is electrically connected to the region 653.The electrode 686, which is the other of the source electrode and thedrain electrode of the TFT 693 and which is one of the source electrodeand the drain electrode of the TFT 694, is electrically connected to theregion 654 and the region 663. The electrode 687, which is the other ofthe source electrode and the drain electrode of the TFT 694, iselectrically connected to the region 664. Thus, TFTs 693 and 694 form aCMOS circuit 695.

In this embodiment mode, the electrodes 681 to 687 are formed by a CVDmethod, a sputtering method, or the like using an element such asaluminum (Al), tungsten (W), titanium (Ti), tantalum (Ta), molybdenum(Mo), nickel (Ni), cobalt (Co), iron (Fe), platinum (Pt), copper (Cu),gold (Au), silver (Ag), manganese (Mn), neodymium (Nd), carbon (C), orsilicon (Si), or an alloy material or a compound material containing theabove element as its main component, with a single layer structure or astacked structure. An alloy material containing aluminum as its maincomponent corresponds to, for example, a material containing nickel,whose main component is aluminum, or an alloy material containing nickeland one or both of carbon and silicon, whose main component is aluminum.For the electrodes 681 to 687, for example, a stacked structure of abarrier film, an aluminum-silicon (Al—Si) film, and a barrier film, or astacked structure of a barrier film, an aluminum-silicon (Al—Si) film, atitanium nitride (TiN) film, and a barrier film may be preferablyemployed. It is to be noted that the barrier film corresponds to a thinfilm formed using titanium, a nitride of titanium, molybdenum, or anitride of molybdenum. Aluminum and aluminum silicon which have a lowresistance and are inexpensive are optimal materials for forming theelectrodes 681 to 687. In addition, an aluminum alloy film can preventinterdiffusion between silicon and aluminum even when being in contactwith silicon. In addition, generation of a hillock of aluminum oraluminum silicon can be prevented when upper and lower barrier layersare provided.

In this embodiment mode, the electrodes 681 to 687 are formed usingstack layers of a titanium (Ti) film, a titanium nitride film, analuminum (Al) film, and a titanium (Ti) film, which are 60 nm, 50 nm,500 nm, and 100 nm, respectively.

The electrodes 681 to 687 may be formed by using the same material andthe same process as those of a wiring, or the electrodes and the wiringmay be separately formed and then may be connected.

Next, an interlayer insulating film 697 is formed over the electrodes681 to 687 and the interlayer insulating film 672 or over a passivationfilm in the case where the passivation film is formed (FIG. 19A). Theinterlayer insulating film 697 may be formed of a similar material tothat of the interlayer insulating film 672.

In the interlayer insulating film 672, a contact hole 851 reaching theelectrode 681, a contact hole 852 reaching the electrode 682, a contacthole 853 reaching the electrode 683, a contact hole 854 reaching theelectrode 684, a contact hole 855 reaching the electrode 685, a contacthole 856 reaching the electrode 686, and a contact hole 857 reaching theelectrode 687 are formed (FIG. 19B).

Then, the whole substrate is soaked in an electrolyte. The electrolytemay be an electrolyte capable of dissolving the material of theelectrodes 681 to 687. The combination of the material for forming theelectrodes 681 to 687 and the electrolyte may be selected from thoseshown in Table 1 described in Embodiment Mode 1. Note that the objectsoaked in the electrolyte does not need to be the whole substrate aslong as the electrode can be dissolved.

When the electrode is soaked in the electrolyte and is applied with avoltage, metal on a surface of the electrode dissociates as ions intothe electrolyte, so that the electrode material is dissolved. As shownin FIG. 20A, a part of the electrode 683 is dissolved so that aseparation region 860 is formed.

Next, as shown in FIG. 20B, a wiring 871 electrically connected to theelectrode 681, a wiring 872 electrically connected to the electrode 682,a wiring 874 electrically connected to the electrode 684, a wiring 875electrically connected to the electrode 685, a wiring 876 electricallyconnected to the electrode 686, and a wiring 877 electrically connectedto the electrode 687 are formed over the interlayer insulating film 697.

A wiring 873 is formed over the interlayer insulating film 672 and overthe electrode 683. Since the wiring 873 is formed so as to reach theseparation region 860, the wiring 873 is not electrically connected tothe electrode 683.

The wirings 871 to 877 may be formed of any of the above-describedmaterials for forming the electrode 681 and the like.

In the above-described manner, TFTs of a memory cell array and TFTs of alogic circuit are formed over the same substrate.

This embodiment mode can be implemented in combination with any of otherembodiment modes and embodiments as needed.

Embodiment Mode 3

Embodiment Mode 3 will describe a manufacturing method of asemiconductor device capable of wireless communication that uses an IC,which is different from those in Embodiment Modes 1 and 2 with referenceto FIG. 14, FIGS. 21A and 21B, FIGS. 22A and 22B, and FIG. 23. In thisembodiment mode, components which are the same as those in EmbodimentMode 1 or Embodiment Mode 2 are denoted by the same reference numerals.

First, in accordance with the description in Embodiment Mode 2, asemiconductor device shown in FIG. 20B is manufactured. Note thatinstead of the base film 602, a separation layer 802, a first base film803, and a second base film 804 are formed.

The separation layer 802 is formed of an amorphous semiconductor film, apolycrystalline semiconductor film, or a semi-amorphous semiconductorfilm. For example, a layer mainly containing silicon such as amorphoussilicon, polycrystalline silicon, single-crystalline silicon, orsemi-amorphous silicon. The separation layer 802 can be formed by asputtering method, a plasma CVD method, or the like. In this embodimentmode, the separation layer 802 is formed of amorphous silicon inapproximately 500 nm thick by a sputtering method.

Note that a semi-amorphous semiconductor film (hereinafter also referredto as a SAS film) includes a semiconductor which has a structureintermediate between an amorphous semiconductor film and a semiconductorfilm having a crystalline structure (including single-crystalline andpolycrystalline structures). The semi-amorphous semiconductor film has athird state which is stable in terms of free energy and is a crystallinesubstance having short-range order and lattice distortion. The crystalgrain of which the size is 0.5 to 20 nm can exist by being dispersed ina non-single crystalline semiconductor film. The peak of the Ramanspectrum of a semi-amorphous semiconductor film is shifted to be lowerthan the frequency of 520 cm⁻¹, and the diffraction peaks of (111) and(220) that are thought to be caused by an Si crystal lattice areobserved by X-ray diffraction. In addition, the semi-amorphoussemiconductor film contains hydrogen or halogen of at least 1 atomic %or more to terminate a dangling bond. In this specification, such asemiconductor film is referred to as a semi-amorphous semiconductor(SAS) film for the sake of convenience. Moreover, a rare gas elementsuch as helium, argon, krypton, or neon may be contained therein tofurther promote lattice distortion so that stability is enhanced and afavorable semi-amorphous semiconductor film can be obtained. Note that amicrocrystalline semiconductor film (microcrystal semiconductor film) isalso included in the semi-amorphous semiconductor film.

In addition, the SAS film can be obtained by glow dischargedecomposition of a gas containing silicon. For a typical gas containingsilicon, SiH₄ is given, and, in addition, Si₂H₆, SiH₂Cl₂, SiHCl₃, SiCl₄,SiF₄, or the like can be used. The gas containing silicon may be dilutedwith hydrogen or with a gas in which one or more of rare gas elements ofhelium, argon, krypton, and neon are added to hydrogen; therefore, theSAS film can be easily formed. It is preferable that the gas containingsilicon be diluted at a dilution rate set to be in the range of 2 to1000 times. Further, a carbide gas such as CH₄ or C₂H₆, a germanium gassuch as GeH₄ or GeF₄, F₂, or the like may be mixed into the gascontaining silicon so as to adjust the energy bandwidth to be from 1.5to 2.4 eV or 0.9 to 1.1 eV.

Each of the base films 803 and 804 includes an insulating film such as asilicon oxide film, a silicon nitride film, a silicon nitride filmcontaining oxygen, or a silicon oxide film containing nitrogen. In thisembodiment mode, a silicon nitride film containing oxygen with athickness of 10 to 200 nm as the first base film 803 and a silicon oxidefilm containing nitrogen with a thickness of 50 to 200 nm as the secondbase film 804 are sequentially stacked and formed.

In accordance with the description in Embodiment Mode 2, the process upto formation of wirings 871 to 877 is performed. Then, an interlayerinsulating film 806 is formed over an interlayer insulating film 697,and electrodes 811 to 816 functioning as antennas are formed. Theelectrodes 811 to 816 functioning as the antennas are formed of aconductive material by a CVD method, a sputtering method, a printingmethod such as screen printing or gravure printing, a droplet dischargemethod, a dispenser method, a plating method, or the like. Theconductive material may be an element of aluminum (Al), titanium (Ti),silver (Ag), copper (Cu), gold (Au), platinum (Pt), nickel (Ni),palladium (Pd), tantalum (Ta), or molybdenum (Mo), or an alloy materialor a compound material containing the element as its main component, andformed using a single layer structure or a stacked structure.

A protective layer 807 is formed over the third interlayer insulatingfilm 806 so as to cover the electrodes 811 to 816 functioning as theantennas. For the protective layer 807, a material is used which canprotect the electrodes 811 to 816 functioning as the antennas when theseparation layer 802 is later removed by etching. For example, theprotective layer 807 can be formed by application of an epoxy basedresin, an acrylate based resin, or a silicon based resin, which issoluble in water or in alcohols, over an entire surface (FIG. 21A).

Next, a groove 808 for separating the separation layer 802 is formed(FIG. 21B). The groove 808 may be formed at least to expose theseparation layer 802. The groove 808 can be formed by etching, dicing,scribing, laser irradiation, or the like.

Then, the separation layer 802 is removed by etching (FIG. 22A). In thisembodiment mode, halogen fluoride is used as an etching gas which isinlet through the groove 808. In this embodiment mode, for example,etching is performed by using ClF₃ (chlorine trifluoride) at 350° C. ata flow rate of 300 sccm with a pressure of 800 Pa for 3 hours. Further,a ClF₃ gas mixed with nitrogen may be used as well. By using halogenfluoride such as ClF₃, the separation layer 802 is selectively etched sothat a substrate 601 can be separated. It is to be noted that halogenfluoride may be either a gas or liquid.

Next, a memory cell array including TFTs 691 and 692 and a logic circuitincluding TFTs 693 and 694, which are separated, are attached to asupport base 821 with an adhesive 822 (FIG. 22B). As the adhesive 822, amaterial capable of attaching the support base 821 to the first basefilm 803 is used. For example, various curable adhesives such as areaction curable adhesive, a heat curable adhesive, a light curableadhesive such as an ultraviolet curable adhesive, and an anaerobioticadhesive can be used as the adhesive 822.

As the support base 821, an organic material such as a flexible paper orplastic can be used. Alternatively, a flexible inorganic material may beused as the support base 821. It is preferable that the support base 821have a heat conductivity as high as 2 to 30 W/mK for dispersing heatgenerated at the integrated circuit.

The integrated circuit including the memory cell array and the logiccircuit can be separated from the substrate 601 by various methods aswell as by etching of a layer mainly containing silicon as described inthis embodiment mode. For example, a metal oxide film is providedbetween a substrate having high heat resistance and the integratedcircuit and the metal oxide film is made vulnerable by crystallization,thereby the integrated circuit can be separated. Further, for example,the separation layer is broken by laser light irradiation so that theintegrated circuit can be separated from the substrate. Moreover, forexample, the substrate over which the integrated circuit is formed canbe mechanically removed or removed by etching with a solution or a gas,so that the integrated circuit can be separated from the substrate.

In the case where an object has a curved surface and thus a support baseof a semiconductor device which is attached to the curved surface andincludes a memory cell array and a logic circuit is bent so as to have acurved surface along a generating line of a conical surface, a columnarsurface, or the like, it is preferable that the direction of thegenerating line and a direction that carriers of a TFT move be the same.By the aforementioned structure, it can be prevented thatcharacteristics of a TFT are affected when the support base is bent.Further, when the island-shaped semiconductor film occupies 1 to 30% ofan area of the integrated circuit, even though the support base is bent,an affect to the characteristics of a TFT can be prevented.

Through the above-described manufacturing process, a semiconductordevice capable of wireless communication that uses an IC according tothe present invention is manufactured.

In this embodiment mode, the antennas are formed over the substrate overwhich the semiconductor device is formed. However, after formation of asemiconductor device, an antenna may be formed by a printing method overa substrate over which the semiconductor device is formed.Alternatively, an antenna may be separately formed over a substratewhich is different from a substrate over which a semiconductor device isformed, and the substrate over which the semiconductor device is formedand the substrate over which the antenna is formed may be attached toeach other, so that the semiconductor device may be electricallyconnected to the antenna.

An example of separately forming an antenna over a substrate which isdifferent from a substrate over which a semiconductor device is formed,attaching the substrate over which the semiconductor device is formed tothe substrate over which the antenna is formed, and electricallyconnecting the semiconductor device to the antenna will be describedwith reference to FIG. 23 and FIG. 14.

Over a substrate 1601 over which a semiconductor device 1602 including amemory cell array and a logic circuit is provided, a terminal portion1605 including a terminal electrode and the like is provided.

Then, the terminal portion 1605 is electrically connected to an antenna1612 which is provided over a substrate 1611 which is different from thesubstrate 1601. The substrate 1601 and the substrate 1611 over which theantenna 1612 is formed are attached so as to connect to the terminalportion 1605. A conductive particle 1603 and a resin 1604 are providedbetween the substrate 1601 and the substrate 1611. With the conductiveparticle 1603, the antenna 1612 and the terminal portion 1605 areelectrically connected. Note that the antenna 1612 shown in FIG. 23 isequivalent to an antenna 917 shown in FIG. 14, and the antenna 1612 andthe antenna 917 are electrically connected to a ground potential (GND)and circuits such as a power supply circuit 915 and a high-frequencycircuit 914.

This embodiment mode can be implemented in combination with any of otherembodiment modes and embodiments.

Embodiment 1

Embodiment 1 will describe a structure and operation of a semiconductordevice capable of wireless communication that uses an IC, which isformed using the present invention, with reference to FIG. 2, FIG. 10,and FIG. 14.

First, the structure is described. As shown in FIG. 14, a semiconductordevice (also referred to as an ID chip, an IC chip, an IC tag, an IDtag, a wireless chip, or an RFID) 931 formed using the present inventionincludes circuit blocks of an antenna 917, a high-frequency circuit 914,a power supply circuit 915, a reset circuit 911, a rectifier circuit906, a demodulation circuit 907, an analog amplifier 908, a clockgeneration circuit 903, a modulation circuit 909, a signal outputcontrol circuit 901, a CRC circuit 902, and a mask ROM 900. The powersupply circuit 915 includes circuit blocks of a rectifier circuit and astorage capacitor. Further, as shown in FIG. 13, the mask ROM 900includes a memory cell array 920, a column decoder 921, and a rowdecoder 922.

As the antenna 917, any of a dipole antenna, a patch antenna, a loopantenna, and a Yagi antenna can be used.

In addition, as a method for transmitting and receiving a wirelesssignal in the antenna 917, any of an electromagnetic coupling method, anelectromagnetic induction method, and an electromagnetic wave method maybe used.

The semiconductor device 931 formed using the present invention isapplied to a semiconductor device 221 shown in FIG. 2.

Next, the operation of the semiconductor device 931 formed using thepresent invention is described. A wireless signal is transmitted from anantenna unit 222 which is electrically connected to an interrogator(also referred to as a reader/writer) 223. The wireless signal includesan instruction from the interrogator (also referred to as areader/writer) 223 to the semiconductor device 931.

The wireless signal received by the antenna 917 is transmitted to eachcircuit block via the high-frequency circuit 914. The signal transmittedto the power supply circuit 915 via the high-frequency circuit 914 isinput to the rectifier circuit.

Here, the rectifier circuit has an action of rectifying a polarity ofthe wireless signal. The signal is rectified and then smoothened by thestorage capacitor. Then, a high power supply potential (VDD) isgenerated.

The wireless signal received by the antenna 917 is also transmitted tothe rectifier circuit 906 via the high-frequency circuit 914. The signalis rectified and then demodulated by the demodulation circuit 907. Thedemodulated signal is amplified by the analog amplifier 908.

Further, the wireless signal received by the antenna 917 is alsotransmitted to the clock generation circuit 903 via the high-frequencycircuit 914. The signal transmitted to the clock generation circuit 903is frequency-divided to be a reference clock signal. Here, the referenceclock signal is transmitted to each circuit block and used for latchinga signal, selecting a signal, and the like.

The signal amplified by the analog amplifier 908 and the reference clocksignal are transmitted to a code extraction circuit 904. In the codeextraction circuit 904, an instruction transmitted from the interrogator(also referred to as a reader/writer) 223 to the semiconductor device931 is extracted from the signal amplified by the analog amplifier 908.The code extraction circuit 904 also forms a signal for controlling acode identification circuit 905.

The instruction extracted by the code extraction circuit 904 istransmitted to the code identification circuit 905. The codeidentification circuit 905 identifies the instruction transmitted fromthe interrogator (also referred to as a reader/writer) 223. The codeidentification circuit 905 also has a role of controlling the CRCcircuit 902, the mask ROM 900, and the signal output control circuit901.

In this manner, the instruction transmitted from the interrogator (alsoreferred to as a reader/writer) 223 is identified, and the CRC circuit902, the mask ROM 900, and the signal output control circuit 901 areoperated in accordance with the identified instruction. In addition, asignal including individual data such as an ID number which is stored inor written to the mask ROM 900, is output.

Here, the mask ROM 900 includes the memory cell array 920, the columndecoder 921, and the row decoder 922.

The signal output control circuit 901 has a role of converting thesignal including the individual data such as the ID number which isstored in or written to the mask ROM 900 into a signal encoded by anencoding method to which a standard of the ISO or the like is applied.

Last, in accordance with the encoded signal, the signal transmitted tothe antenna 917 is modulated by the modulation circuit 909.

The modulated signal is received by the antenna unit 222 which iselectrically connected to the interrogator (also referred to as areader/writer) 223. Then, the received signal is analyzed by theinterrogator (also referred to as a reader/writer) 223, so that theindividual data such as the ID number of the semiconductor device 931formed using the present invention can be recognized.

In a wireless communication system using the semiconductor device 931capable of wireless communication that uses an IC, formed using thepresent invention, the semiconductor device 931, an interrogator (alsoreferred to as a reader/writer) having a known structure, an antennaelectrically connected to the interrogator (also referred to as areader/writer), and a control terminal for controlling the interrogator(also referred to as a reader/writer) can be used. A communicationmethod of the semiconductor device 931 and the antenna electricallyconnected to the interrogator (also referred to as a reader/writer) is aone-way communication or two-way communication, and any of a spacedivision multiplexing method, a polarization division multiplexingmethod, a frequency-division multiplexing method, a time-divisionmultiplexing method, a code division multiplexing method, and anorthogonal frequency division multiplexing method can also be used.

The wireless signal is a signal in which a carrier wave is modulated.Modulation of a carrier wave is an analog modulation or a digitalmodulation, which may be any of an amplitude modulation, a phasemodulation, a frequency modulation, and spread spectrum.

As for a frequency of a carrier wave, any of the following can beemployed: a submillimeter wave of greater than or equal to 300 GHz andless than or equal to 3 THz; an extra high frequency of greater than orequal to 30 GHz and less than 300 GHz; a super high frequency of greaterthan or equal to 3 GHz and less than 30 GHz; an ultra high frequency ofgreater than or equal to 300 MHz and less than 3 GHz; a very highfrequency of greater than or equal to 30 MHz and less than 300 MHz; ahigh frequency of greater than or equal to 3 MHz and less than 30 MHz; amedium frequency of greater than or equal to 300 KHz and less than 3MHz; a low frequency of greater than or equal to 30 KHz and less than300 KHz; and a very low frequency of greater than or equal to 3 KHz andless than 30 KHz.

This embodiment can be implemented in combination with any of theembodiment modes or other embodiments if needed.

Embodiment 2

Embodiment 2 will describe examples in which an external antenna isprovided for a semiconductor device formed using the present invention,with reference to FIGS. 24A to 24E and FIGS. 25A and 25B.

FIG. 24A shows a case where a sheet of antenna covers the periphery of asemiconductor device. An antenna 1001 is formed over a substrate 1000and a semiconductor device 1002 formed using the present invention iselectrically connected thereto. In FIG. 24A, the antenna 1001 covers theperiphery of the semiconductor device 1002, however, the antenna 1001may cover the entire surface of the substrate and the semiconductordevice 1002 having electrodes may be attached thereto.

FIG. 24B shows an example of a coil antenna in which an antenna isarranged to circle around a semiconductor device. An antenna 1004 isformed over a substrate 1003 and a semiconductor device 1005 formedusing the present invention is connected thereto. It is to be noted thatthe arrangement of the antenna is only an example and the invention isnot limited to this.

FIG. 24C shows an antenna for high frequency. An antenna 1007 is formedover a substrate 1006 and a semiconductor device 1008 formed using thepresent invention is electrically connected thereto.

FIG. 24D shows a 180° omni-directional antenna (capable of receivingsignals equally from any directions). An antenna 1010 is formed over asubstrate 1009 and a semiconductor device 1011 formed using the presentinvention is electrically connected thereto.

FIG. 24E shows an antenna extended in a stick shape. An antenna 1013 isformed over a substrate 1012 and a semiconductor device 1014 formedusing the present invention is electrically connected thereto.

Further, FIG. 25A shows another example of a coil antenna. An antenna1016 is formed over a substrate 1015, and a semiconductor device 1017formed using the present invention is electrically connected thereto.One end portion of the antenna 1016 is connected to the semiconductordevice 1017. The other end portion of the antenna 1016 is connected to awiring 1018 which is formed in a different process from that of theantenna 1016, and is electrically connected to the semiconductor device1017 through the wiring 1018. In FIG. 25A, the wiring 1018 is formedover the antenna 1016; however, it may be formed below the antenna 1016.

FIG. 25B shows another example of a coil antenna. An antenna 1026 isformed over a substrate 1025, and a semiconductor device 1027 formedusing the present invention is electrically connected thereto. One endportion of the antenna 1026 is connected to the semiconductor device1027. The other end portion of the antenna 1026 is connected to a wiring1028 which is formed in a different process from that of the antenna1026, and is electrically connected to the semiconductor device 1027through the wiring 1028. In FIG. 25B, the wiring 1028 is formed over theantenna 1026; however, it may be formed below the antenna 1026.

A semiconductor device formed using the present invention and theabove-described antenna can be connected by a known method. For example,the antenna and the semiconductor device are connected by wire bondingor bump bonding. Alternatively, a circuit chip having an electrode on anentire surface thereof may be attached to the antenna; in this method,an ACF (anisotropic conductive film) can be used for the attachment.

An appropriate length of the antenna varies depending on a frequency forreceiving signals. For example, when the frequency is 2.45 GHz, in thecase of providing a half-wave dipole antenna, the length of the antennamay be a half wavelength (about 60 mm), and in the case of providing amonopole antenna, the length may be a quarter wavelength (about 30 mm).

It is to be noted that the example shown in this embodiment is only anexample and the shape of the antenna is not limited. The presentinvention can be implemented with any shape of the antenna. Thisembodiment can be implemented by using any combination with the aboveembodiment modes and the other embodiments.

Embodiment 3

Embodiment 3 will describe a method for forming a separation regiondifferently from that in Embodiment Mode 1, with reference to FIGS. 26Ato 26C.

In Embodiment Mode 1, the electrode 110 is in contact with theelectrolyte through the contact hole 168 which is formed in theinsulating film 135 as shown in FIG. 9B. However, in this embodimentmode, one portion of an insulating film is removed in advance, and anopening portion is formed. Then, an electrode or wiring formed in theopening portion is soaked in an electrolyte while being applied with avoltage, so that the electrode or wiring is removed.

As shown in FIG. 26A, an opening portion 252 is provided in aninsulating film 251. Further, an electrode or wiring 253 is formed inthe opening portion 252. Note that the electrode or wiring 253 is formedover the insulating film 251 in FIG. 26A; however, according to need,the insulating film 251 may be formed over the electrode or wiring 253and then the opening portion 252 may be formed.

Then, the electrode or wiring 253 in the opening portion 252 is soakedin an electrolyte while being applied with a voltage, thereby dissolvingthe electrode or wiring 253. Thus, a separation region 254 is formed(FIG. 26B). As the material for the electrode or wiring 253 and theelectrolyte, those shown in Table 1 may be employed.

Next, an electrode or wiring 255 is formed in the separation region 254.The electric connection between the electrode or wiring 253 and theelectrode or wiring 255 is blocked by the separation region 254.

This embodiment can be implemented in combination with any of theembodiment modes and the other embodiments as needed.

A semiconductor device of the present invention can be utilized for anIC tag which is used in a distribution field as a shipping tag for beingattached to a packing box of a product or to the product itself. Inaddition, the semiconductor device can be utilized for an IC tag whichis attached to a passenger's luggage in air transport or railwaytransport. Further, in a medical field, when the semiconductor device isattached to a medical chart for example, the medical chart can behandled quickly and accurately. The semiconductor device of the presentinvention can be used in every field in a ubiquitous society.

Data for identification needs to be stored in each of these IC tags.When the present invention is applied, productivity of IC tags in eachof which identification data is stored in advance can be improved, andmanufacturing time and manufacturing cost can be reduced.

This application is based on Japanese Patent Application serial no.2006-199354 filed in Japan Patent Office on Jul. 21, 2006, the entirecontents of which are hereby incorporated by reference.

1. A semiconductor device comprising: a thin film transistor over asubstrate which includes an island-shaped semiconductor film including achannel forming region, a source region and a drain region, a gateinsulating film, and a gate electrode; a first interlayer insulatingfilm formed over the thin film transistor; a first electrode which isformed over the first interlayer insulating film and electricallyconnected to one of the source region and the drain region; a secondelectrode which is formed over the first interlayer insulating film andelectrically connected to the other of the source region and the drainregion; a second interlayer insulating film formed over the firstinterlayer insulating film, the first electrode, and the secondelectrode; a first wiring which is formed on the second interlayerinsulating film and electrically connected to one of the first electrodeand the second electrode; and a second wiring which is formed on thesecond interlayer insulating film and not electrically connected to theother of the first electrode and the second electrode, wherein thesecond wiring is not electrically connected to the other of the firstelectrode and the second electrode by a separation region which isformed in the second interlayer insulating film.
 2. A semiconductordevice comprising: a first thin film transistor over a substrate whichincludes a first island-shaped semiconductor film including a firstchannel forming region, a first source region and a first drain region,a gate insulating film, and a first gate electrode; a second thin filmtransistor which includes a second island-shaped semiconductor filmincluding a second channel forming region, a second source region and asecond drain region, the gate insulating film, and a second gateelectrode; a first interlayer insulating film formed over the first thinfilm transistor and the second thin film transistor; a first electrodewhich is formed over the first interlayer insulating film andelectrically connected to one of the first source region and the firstdrain region; a second electrode which is formed over the firstinterlayer insulating film and electrically connected to the other ofthe first source region and the first drain region; a third electrodewhich is formed over the first interlayer insulating film andelectrically connected to one of the second source region and the seconddrain region; a fourth electrode which is formed over the firstinterlayer insulating film and electrically connected to the other ofthe second source region and the second drain region; a secondinterlayer insulating film formed over the first interlayer insulatingfilm and the first to fourth electrodes; a first wiring which is formedon the second interlayer insulating film and electrically connected tothe first electrode; a second wiring which is formed on the secondinterlayer insulating film and electrically connected to the secondelectrode; a third wiring which is formed on the second interlayerinsulating film and not electrically connected to the third electrode;and a fourth wiring which is formed on the second interlayer insulatingfilm and electrically connected to the fourth electrode, wherein thethird wiring is not electrically connected to the third electrode by aseparation region which is formed in the second interlayer insulatingfilm.
 3. The semiconductor device according to claim 1, wherein the thinfilm transistor is used in a nonvolatile memory circuit.
 4. Thesemiconductor device according to claim 2, wherein the first thin filmtransistor and the second thin film transistor are used in a nonvolatilememory circuit.